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Groups > linux.kernel > #1187251 > unrolled thread
| Started by | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| First post | 2015-07-18 00:40 +0200 |
| Last post | 2015-07-18 00:40 +0200 |
| Articles | 13 — 1 participant |
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[PATCH tip/core/rcu 0/12] Tree geometry-initialization simplifications for 4.3 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 03/12] rcu: Remove superfluous local variable in rcu_init_geometry() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 08/12] rcu: Remove unnecessary fields from rcu_state structure "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 12/12] rcu: Reset rcu_fanout_leaf if out of bounds "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 11/12] rcu: Shut up bogus gcc array bounds warning "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 10/12] rcu: Simplify arithmetic to calculate number of RCU nodes "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 05/12] rcu: Simplify rcu_init_geometry() capacity arithmetics "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 09/12] rcu: Limit count of static data to the number of RCU levels "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 01/12] rcu: Provide more diagnostics for stalled GP kthread "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 04/12] rcu: Cleanup rcu_init_geometry() code and arithmetics "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 02/12] rcu: Panic if RCU tree can not accommodate all CPUs "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 07/12] rcu: Limit rcu_capacity[] size to RCU_NUM_LVLS items "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
[PATCH tip/core/rcu 06/12] rcu: Limit rcu_state::levelcnt[] to RCU_NUM_LVLS items "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-18 00:40 +0200
| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 0/12] Tree geometry-initialization simplifications for 4.3 |
| Message-ID | <pNmsp-2cc-1@gated-at.bofh.it> |
Hello! This series simplifies the arithmetic involved in computing the geometry of Tree RCU's combining tree. 1. Provide more diagnostics for stalled GP kthread. (A bit off-topic, but included in this series due to conflicting updates.) 2. Panic if RCU tree can not accommodate all CPUs, courtesy of Alexander Gordeev. 3. Remove superfluous local variable in rcu_init_geometry(), courtesy of Alexander Gordeev. 4. Cleanup rcu_init_geometry() code and arithmetic, courtesy of Alexander Gordeev. 5. Simplify rcu_init_geometry() capacity arithmetic, courtesy of Alexander Gordeev. 6. Limit rcu_state::levelcnt[] to RCU_NUM_LVLS items, courtesy of Alexander Gordeev. 7. Limit rcu_capacity[] size to RCU_NUM_LVLS items, courtesy of Alexander Gordeev. 8. Remove unnecessary fields from rcu_state structure, courtesy of Alexander Gordeev. 9. Limit count of static data to the number of RCU levels, courtesy of Alexander Gordeev. 10. Simplify arithmetic to calculate number of RCU nodes, courtesy of Alexander Gordeev. 11. Shut up bogus gcc array bounds warning, courtesy of Alexander Gordeev. 12. Reset rcu_fanout_leaf if out of bounds. Thanx, Paul ------------------------------------------------------------------------ b/kernel/rcu/tree.c | 156 +++++++++++++++++++++------------------------ b/kernel/rcu/tree.h | 45 +++++++----- b/kernel/rcu/tree_plugin.h | 4 - 3 files changed, 103 insertions(+), 102 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 03/12] rcu: Remove superfluous local variable in rcu_init_geometry() |
| Message-ID | <pNmsq-2cc-5@gated-at.bofh.it> |
| In reply to | #1187251 |
From: Alexander Gordeev <agordeev@redhat.com>
Local variable 'n' mimics 'nr_cpu_ids' while the both are
used within one function. There is no reason for 'n' to
exist whatsoever.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index fe8d92987dfa..ad49dbed44fb 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4083,7 +4083,6 @@ static void __init rcu_init_geometry(void)
ulong d;
int i;
int j;
- int n = nr_cpu_ids;
int rcu_capacity[MAX_RCU_LVLS + 1];
/*
@@ -4133,15 +4132,16 @@ static void __init rcu_init_geometry(void)
* The tree must be able to accommodate the configured number of CPUs.
* If this limit is exceeded than we have a serious problem elsewhere.
*/
- if (n > rcu_capacity[MAX_RCU_LVLS])
+ if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS])
panic("rcu_init_geometry: rcu_capacity[] is too small");
/* Calculate the number of rcu_nodes at each level of the tree. */
for (i = 1; i <= MAX_RCU_LVLS; i++)
- if (n <= rcu_capacity[i]) {
- for (j = 0; j <= i; j++)
- num_rcu_lvl[j] =
- DIV_ROUND_UP(n, rcu_capacity[i - j]);
+ if (nr_cpu_ids <= rcu_capacity[i]) {
+ for (j = 0; j <= i; j++) {
+ int cap = rcu_capacity[i - j];
+ num_rcu_lvl[j] = DIV_ROUND_UP(nr_cpu_ids, cap);
+ }
rcu_num_lvls = i;
for (j = i + 1; j <= MAX_RCU_LVLS; j++)
num_rcu_lvl[j] = 0;
@@ -4152,7 +4152,7 @@ static void __init rcu_init_geometry(void)
rcu_num_nodes = 0;
for (i = 0; i <= MAX_RCU_LVLS; i++)
rcu_num_nodes += num_rcu_lvl[i];
- rcu_num_nodes -= n;
+ rcu_num_nodes -= nr_cpu_ids;
}
/*
--
1.8.1.5
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 08/12] rcu: Remove unnecessary fields from rcu_state structure |
| Message-ID | <pNmsq-2cc-13@gated-at.bofh.it> |
| In reply to | #1187251 |
From: Alexander Gordeev <agordeev@redhat.com>
Members rcu_state::levelcnt[] and rcu_state::levelspread[]
are only used at init. There is no reason to keep them
afterwards.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 27 +++++++++++++++------------
kernel/rcu/tree.h | 2 --
2 files changed, 15 insertions(+), 14 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 2ec7b796f660..7226e25ba97f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3967,22 +3967,22 @@ void rcu_scheduler_starting(void)
* Compute the per-level fanout, either using the exact fanout specified
* or balancing the tree, depending on the rcu_fanout_exact boot parameter.
*/
-static void __init rcu_init_levelspread(struct rcu_state *rsp)
+static void __init rcu_init_levelspread(int *levelspread, const int *levelcnt)
{
int i;
if (rcu_fanout_exact) {
- rsp->levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
+ levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
for (i = rcu_num_lvls - 2; i >= 0; i--)
- rsp->levelspread[i] = RCU_FANOUT;
+ levelspread[i] = RCU_FANOUT;
} else {
int ccur;
int cprv;
cprv = nr_cpu_ids;
for (i = rcu_num_lvls - 1; i >= 0; i--) {
- ccur = rsp->levelcnt[i];
- rsp->levelspread[i] = (cprv + ccur - 1) / ccur;
+ ccur = levelcnt[i];
+ levelspread[i] = (cprv + ccur - 1) / ccur;
cprv = ccur;
}
}
@@ -4005,6 +4005,9 @@ static void __init rcu_init_one(struct rcu_state *rsp,
"rcu_node_fqs_2",
"rcu_node_fqs_3" };
static u8 fl_mask = 0x1;
+
+ int levelcnt[RCU_NUM_LVLS]; /* # nodes in each level. */
+ int levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
int cpustride = 1;
int i;
int j;
@@ -4019,19 +4022,19 @@ static void __init rcu_init_one(struct rcu_state *rsp,
/* Initialize the level-tracking arrays. */
for (i = 0; i < rcu_num_lvls; i++)
- rsp->levelcnt[i] = num_rcu_lvl[i];
+ levelcnt[i] = num_rcu_lvl[i];
for (i = 1; i < rcu_num_lvls; i++)
- rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1];
- rcu_init_levelspread(rsp);
+ rsp->level[i] = rsp->level[i - 1] + levelcnt[i - 1];
+ rcu_init_levelspread(levelspread, levelcnt);
rsp->flavor_mask = fl_mask;
fl_mask <<= 1;
/* Initialize the elements themselves, starting from the leaves. */
for (i = rcu_num_lvls - 1; i >= 0; i--) {
- cpustride *= rsp->levelspread[i];
+ cpustride *= levelspread[i];
rnp = rsp->level[i];
- for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
+ for (j = 0; j < levelcnt[i]; j++, rnp++) {
raw_spin_lock_init(&rnp->lock);
lockdep_set_class_and_name(&rnp->lock,
&rcu_node_class[i], buf[i]);
@@ -4051,10 +4054,10 @@ static void __init rcu_init_one(struct rcu_state *rsp,
rnp->grpmask = 0;
rnp->parent = NULL;
} else {
- rnp->grpnum = j % rsp->levelspread[i - 1];
+ rnp->grpnum = j % levelspread[i - 1];
rnp->grpmask = 1UL << rnp->grpnum;
rnp->parent = rsp->level[i - 1] +
- j / rsp->levelspread[i - 1];
+ j / levelspread[i - 1];
}
rnp->level = i;
INIT_LIST_HEAD(&rnp->blkd_tasks);
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index d625e9ff0faf..3413f3c5c8b2 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -441,8 +441,6 @@ do { \
struct rcu_state {
struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
- u32 levelcnt[RCU_NUM_LVLS]; /* # nodes in each level. */
- u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
u8 flavor_mask; /* bit in flavor mask. */
struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
--
1.8.1.5
--
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 12/12] rcu: Reset rcu_fanout_leaf if out of bounds |
| Message-ID | <pNmsq-2cc-15@gated-at.bofh.it> |
| In reply to | #1187251 |
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Currently if the rcu_fanout_leaf boot parameter is out of bounds (that
is, less than RCU_FANOUT_LEAF or greater than the number of bits in an
unsigned long), a warning is issued and execution continues with the
out-of-bounds value. This can result in all manner of failures, so this
patch resets rcu_fanout_leaf to RCU_FANOUT_LEAF when an out-of-bounds
condition is detected.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e53bbc53bcd5..a2147d7b51c0 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4103,6 +4103,7 @@ static void __init rcu_init_geometry(void)
*/
if (rcu_fanout_leaf < RCU_FANOUT_LEAF ||
rcu_fanout_leaf > sizeof(unsigned long) * 8) {
+ rcu_fanout_leaf = RCU_FANOUT_LEAF;
WARN_ON(1);
return;
}
--
1.8.1.5
--
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 11/12] rcu: Shut up bogus gcc array bounds warning |
| Message-ID | <pNmsq-2cc-17@gated-at.bofh.it> |
| In reply to | #1187251 |
From: Alexander Gordeev <agordeev@redhat.com>
Because gcc does not realize a loop would not be entered ever
(i.e. in case of rcu_num_lvls == 1):
for (i = 1; i < rcu_num_lvls; i++)
rsp->level[i] = rsp->level[i - 1] + levelcnt[i - 1];
some compiler (pre- 5.x?) versions give a bogus warning:
kernel/rcu/tree.c: In function ‘rcu_init_one.isra.55’:
kernel/rcu/tree.c:4108:13: warning: array subscript is above array bounds [-Warray-bounds]
rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1];
^
Fix that warning by adding an extra item to rcu_state::level[]
array. Once the bogus warning is fixed in gcc and kernel drops
support of older versions, the dummy item may be removed from
the array.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Suggested-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 581f8d3c5b28..faee5242d6ff 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -443,7 +443,9 @@ do { \
*/
struct rcu_state {
struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
- struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
+ struct rcu_node *level[RCU_NUM_LVLS + 1];
+ /* Hierarchy levels (+1 to */
+ /* shut bogus gcc warning) */
u8 flavor_mask; /* bit in flavor mask. */
struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
--
1.8.1.5
--
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 10/12] rcu: Simplify arithmetic to calculate number of RCU nodes |
| Message-ID | <pNmsq-2cc-23@gated-at.bofh.it> |
| In reply to | #1187251 |
From: Alexander Gordeev <agordeev@redhat.com>
This update makes arithmetic to calculate number of RCU nodes
more straight and easy to read.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.h | 17 ++++-------------
kernel/rcu/tree_plugin.h | 4 ++--
2 files changed, 6 insertions(+), 15 deletions(-)
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index d44856b6170a..581f8d3c5b28 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -64,10 +64,7 @@
#if NR_CPUS <= RCU_FANOUT_1
# define RCU_NUM_LVLS 1
# define NUM_RCU_LVL_0 1
-# define NUM_RCU_LVL_1 (NR_CPUS)
-# define NUM_RCU_LVL_2 0
-# define NUM_RCU_LVL_3 0
-# define NUM_RCU_LVL_4 0
+# define NUM_RCU_NODES NUM_RCU_LVL_0
# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0 }
# define RCU_NODE_NAME_INIT { "rcu_node_0" }
# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0" }
@@ -75,9 +72,7 @@
# define RCU_NUM_LVLS 2
# define NUM_RCU_LVL_0 1
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
-# define NUM_RCU_LVL_2 (NR_CPUS)
-# define NUM_RCU_LVL_3 0
-# define NUM_RCU_LVL_4 0
+# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1)
# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1 }
# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1" }
# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1" }
@@ -86,8 +81,7 @@
# define NUM_RCU_LVL_0 1
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
-# define NUM_RCU_LVL_3 (NR_CPUS)
-# define NUM_RCU_LVL_4 0
+# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2)
# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1, NUM_RCU_LVL_2 }
# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1", "rcu_node_2" }
# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2" }
@@ -97,7 +91,7 @@
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
# define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
-# define NUM_RCU_LVL_4 (NR_CPUS)
+# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3)
# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1, NUM_RCU_LVL_2, NUM_RCU_LVL_3 }
# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1", "rcu_node_2", "rcu_node_3" }
# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2", "rcu_node_fqs_3" }
@@ -105,9 +99,6 @@
# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
#endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
-#define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4)
-#define NUM_RCU_NODES (RCU_SUM - NR_CPUS)
-
extern int rcu_num_lvls;
extern int rcu_num_nodes;
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 013485fb2b06..5dac0a10a985 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -84,8 +84,8 @@ static void __init rcu_bootup_announce_oddness(void)
pr_info("\tRCU torture testing starts during boot.\n");
if (IS_ENABLED(CONFIG_RCU_CPU_STALL_INFO))
pr_info("\tAdditional per-CPU info printed with stalls.\n");
- if (NUM_RCU_LVL_4 != 0)
- pr_info("\tFour-level hierarchy is enabled.\n");
+ if (RCU_NUM_LVLS >= 4)
+ pr_info("\tFour(or more)-level hierarchy is enabled.\n");
if (RCU_FANOUT_LEAF != 16)
pr_info("\tBuild-time adjustment of leaf fanout to %d.\n",
RCU_FANOUT_LEAF);
--
1.8.1.5
--
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[toc] | [prev] | [next] | [standalone]
| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 05/12] rcu: Simplify rcu_init_geometry() capacity arithmetics |
| Message-ID | <pNmsq-2cc-25@gated-at.bofh.it> |
| In reply to | #1187251 |
From: Alexander Gordeev <agordeev@redhat.com>
Current code suggests that introducing the extra level to
rcu_capacity[] array makes some of the arithmetic easier.
Well, in fact it appears rather confusing and unnecessary.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 37ca8a867a1c..2103beedb49f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4082,7 +4082,7 @@ static void __init rcu_init_geometry(void)
{
ulong d;
int i;
- int rcu_capacity[MAX_RCU_LVLS + 1];
+ int rcu_capacity[MAX_RCU_LVLS];
/*
* Initialize any unspecified boot parameters.
@@ -4119,29 +4119,27 @@ static void __init rcu_init_geometry(void)
/*
* Compute number of nodes that can be handled an rcu_node tree
- * with the given number of levels. Setting rcu_capacity[0] makes
- * some of the arithmetic easier.
+ * with the given number of levels.
*/
- rcu_capacity[0] = 1;
- rcu_capacity[1] = rcu_fanout_leaf;
- for (i = 2; i <= MAX_RCU_LVLS; i++)
+ rcu_capacity[0] = rcu_fanout_leaf;
+ for (i = 1; i < MAX_RCU_LVLS; i++)
rcu_capacity[i] = rcu_capacity[i - 1] * RCU_FANOUT;
/*
* The tree must be able to accommodate the configured number of CPUs.
* If this limit is exceeded than we have a serious problem elsewhere.
*/
- if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS])
+ if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS - 1])
panic("rcu_init_geometry: rcu_capacity[] is too small");
/* Calculate the number of levels in the tree. */
- for (i = 1; nr_cpu_ids > rcu_capacity[i]; i++) {
+ for (i = 0; nr_cpu_ids > rcu_capacity[i]; i++) {
}
- rcu_num_lvls = i;
+ rcu_num_lvls = i + 1;
/* Calculate the number of rcu_nodes at each level of the tree. */
for (i = 0; i < rcu_num_lvls; i++) {
- int cap = rcu_capacity[rcu_num_lvls - i];
+ int cap = rcu_capacity[(rcu_num_lvls - 1) - i];
num_rcu_lvl[i] = DIV_ROUND_UP(nr_cpu_ids, cap);
}
--
1.8.1.5
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 09/12] rcu: Limit count of static data to the number of RCU levels |
| Message-ID | <pNmsr-2cc-33@gated-at.bofh.it> |
| In reply to | #1187251 |
From: Alexander Gordeev <agordeev@redhat.com>
Although a number of RCU levels may be less than the current
maximum of four, some static data associated with each level
are allocated for all four levels. As result, the extra data
never get accessed and just wast memory. This update limits
count of allocated items to the number of used RCU levels.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 21 ++++-----------------
kernel/rcu/tree.h | 12 ++++++++++++
2 files changed, 16 insertions(+), 17 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7226e25ba97f..e53bbc53bcd5 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -124,13 +124,8 @@ module_param(rcu_fanout_exact, bool, 0444);
static int rcu_fanout_leaf = RCU_FANOUT_LEAF;
module_param(rcu_fanout_leaf, int, 0444);
int rcu_num_lvls __read_mostly = RCU_NUM_LVLS;
-static int num_rcu_lvl[] = { /* Number of rcu_nodes at specified level. */
- NUM_RCU_LVL_0,
- NUM_RCU_LVL_1,
- NUM_RCU_LVL_2,
- NUM_RCU_LVL_3,
- NUM_RCU_LVL_4,
-};
+/* Number of rcu_nodes at specified level. */
+static int num_rcu_lvl[] = NUM_RCU_LVL_INIT;
int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */
/*
@@ -3994,16 +3989,8 @@ static void __init rcu_init_levelspread(int *levelspread, const int *levelcnt)
static void __init rcu_init_one(struct rcu_state *rsp,
struct rcu_data __percpu *rda)
{
- static const char * const buf[] = {
- "rcu_node_0",
- "rcu_node_1",
- "rcu_node_2",
- "rcu_node_3" };
- static const char * const fqs[] = {
- "rcu_node_fqs_0",
- "rcu_node_fqs_1",
- "rcu_node_fqs_2",
- "rcu_node_fqs_3" };
+ static const char * const buf[] = RCU_NODE_NAME_INIT;
+ static const char * const fqs[] = RCU_FQS_NAME_INIT;
static u8 fl_mask = 0x1;
int levelcnt[RCU_NUM_LVLS]; /* # nodes in each level. */
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 3413f3c5c8b2..d44856b6170a 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -68,6 +68,9 @@
# define NUM_RCU_LVL_2 0
# define NUM_RCU_LVL_3 0
# define NUM_RCU_LVL_4 0
+# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0 }
+# define RCU_NODE_NAME_INIT { "rcu_node_0" }
+# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0" }
#elif NR_CPUS <= RCU_FANOUT_2
# define RCU_NUM_LVLS 2
# define NUM_RCU_LVL_0 1
@@ -75,6 +78,9 @@
# define NUM_RCU_LVL_2 (NR_CPUS)
# define NUM_RCU_LVL_3 0
# define NUM_RCU_LVL_4 0
+# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1 }
+# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1" }
+# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1" }
#elif NR_CPUS <= RCU_FANOUT_3
# define RCU_NUM_LVLS 3
# define NUM_RCU_LVL_0 1
@@ -82,6 +88,9 @@
# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
# define NUM_RCU_LVL_3 (NR_CPUS)
# define NUM_RCU_LVL_4 0
+# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1, NUM_RCU_LVL_2 }
+# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1", "rcu_node_2" }
+# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2" }
#elif NR_CPUS <= RCU_FANOUT_4
# define RCU_NUM_LVLS 4
# define NUM_RCU_LVL_0 1
@@ -89,6 +98,9 @@
# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
# define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
# define NUM_RCU_LVL_4 (NR_CPUS)
+# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1, NUM_RCU_LVL_2, NUM_RCU_LVL_3 }
+# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1", "rcu_node_2", "rcu_node_3" }
+# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2", "rcu_node_fqs_3" }
#else
# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
#endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
--
1.8.1.5
--
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 01/12] rcu: Provide more diagnostics for stalled GP kthread |
| Message-ID | <pNmsq-2cc-7@gated-at.bofh.it> |
| In reply to | #1187251 |
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 10 ++++++++--
kernel/rcu/tree.h | 6 +++++-
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 65137bc28b2b..1c58cbd03922 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1178,9 +1178,11 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
j = jiffies;
gpa = READ_ONCE(rsp->gp_activity);
if (j - gpa > 2 * HZ)
- pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x\n",
+ pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d ->state=%#lx\n",
rsp->name, j - gpa,
- rsp->gpnum, rsp->completed, rsp->gp_flags);
+ rsp->gpnum, rsp->completed,
+ rsp->gp_flags, rsp->gp_state,
+ rsp->gp_kthread ? rsp->gp_kthread->state : 0);
}
/*
@@ -2041,6 +2043,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
wait_event_interruptible(rsp->gp_wq,
READ_ONCE(rsp->gp_flags) &
RCU_GP_FLAG_INIT);
+ rsp->gp_state = RCU_GP_DONE_GPS;
/* Locking provides needed memory barrier. */
if (rcu_gp_init(rsp))
break;
@@ -2073,6 +2076,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
(!READ_ONCE(rnp->qsmask) &&
!rcu_preempt_blocked_readers_cgp(rnp)),
j);
+ rsp->gp_state = RCU_GP_DONE_FQS;
/* Locking provides needed memory barriers. */
/* If grace period done, leave loop. */
if (!READ_ONCE(rnp->qsmask) &&
@@ -2110,7 +2114,9 @@ static int __noreturn rcu_gp_kthread(void *arg)
}
/* Handle grace-period end. */
+ rsp->gp_state = RCU_GP_CLEANUP;
rcu_gp_cleanup(rsp);
+ rsp->gp_state = RCU_GP_CLEANED;
}
}
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 4adb7ca0bf47..f1f4784f9107 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -527,7 +527,11 @@ struct rcu_state {
/* Values for rcu_state structure's gp_flags field. */
#define RCU_GP_WAIT_INIT 0 /* Initial state. */
#define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */
-#define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */
+#define RCU_GP_DONE_GPS 2 /* Wait done for grace-period start. */
+#define RCU_GP_WAIT_FQS 3 /* Wait for force-quiescent-state time. */
+#define RCU_GP_DONE_FQS 4 /* Wait done for force-quiescent-state time. */
+#define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */
+#define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */
extern struct list_head rcu_struct_flavors;
--
1.8.1.5
--
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 04/12] rcu: Cleanup rcu_init_geometry() code and arithmetics |
| Message-ID | <pNmsr-2cc-35@gated-at.bofh.it> |
| In reply to | #1187261 |
From: Alexander Gordeev <agordeev@redhat.com>
This update simplifies rcu_init_geometry() code flow
and makes calculation of the total number of rcu_node
structures more easy to read.
The update relies on the fact num_rcu_lvl[] is never
accessed beyond rcu_num_lvls index by the rest of the
code. Therefore, there is no need initialize the whole
num_rcu_lvl[].
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 24 ++++++++++--------------
1 file changed, 10 insertions(+), 14 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index ad49dbed44fb..37ca8a867a1c 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4082,7 +4082,6 @@ static void __init rcu_init_geometry(void)
{
ulong d;
int i;
- int j;
int rcu_capacity[MAX_RCU_LVLS + 1];
/*
@@ -4135,24 +4134,21 @@ static void __init rcu_init_geometry(void)
if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS])
panic("rcu_init_geometry: rcu_capacity[] is too small");
+ /* Calculate the number of levels in the tree. */
+ for (i = 1; nr_cpu_ids > rcu_capacity[i]; i++) {
+ }
+ rcu_num_lvls = i;
+
/* Calculate the number of rcu_nodes at each level of the tree. */
- for (i = 1; i <= MAX_RCU_LVLS; i++)
- if (nr_cpu_ids <= rcu_capacity[i]) {
- for (j = 0; j <= i; j++) {
- int cap = rcu_capacity[i - j];
- num_rcu_lvl[j] = DIV_ROUND_UP(nr_cpu_ids, cap);
- }
- rcu_num_lvls = i;
- for (j = i + 1; j <= MAX_RCU_LVLS; j++)
- num_rcu_lvl[j] = 0;
- break;
- }
+ for (i = 0; i < rcu_num_lvls; i++) {
+ int cap = rcu_capacity[rcu_num_lvls - i];
+ num_rcu_lvl[i] = DIV_ROUND_UP(nr_cpu_ids, cap);
+ }
/* Calculate the total number of rcu_node structures. */
rcu_num_nodes = 0;
- for (i = 0; i <= MAX_RCU_LVLS; i++)
+ for (i = 0; i < rcu_num_lvls; i++)
rcu_num_nodes += num_rcu_lvl[i];
- rcu_num_nodes -= nr_cpu_ids;
}
/*
--
1.8.1.5
--
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 02/12] rcu: Panic if RCU tree can not accommodate all CPUs |
| Message-ID | <pNmsr-2cc-39@gated-at.bofh.it> |
| In reply to | #1187261 |
From: Alexander Gordeev <agordeev@redhat.com>
Currently a condition when RCU tree is unable to accommodate
the configured number of CPUs is not permitted and causes
a fall back to compile-time values. However, the code has no
means to exceed the RCU tree capacity neither at compile-time
nor in run-time. Therefore, if the condition is met in run-
time then it indicates a serios problem elsewhere and should
be handled with a panic.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 1c58cbd03922..fe8d92987dfa 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4107,6 +4107,19 @@ static void __init rcu_init_geometry(void)
rcu_fanout_leaf, nr_cpu_ids);
/*
+ * The boot-time rcu_fanout_leaf parameter is only permitted
+ * to increase the leaf-level fanout, not decrease it. Of course,
+ * the leaf-level fanout cannot exceed the number of bits in
+ * the rcu_node masks. Complain and fall back to the compile-
+ * time values if these limits are exceeded.
+ */
+ if (rcu_fanout_leaf < RCU_FANOUT_LEAF ||
+ rcu_fanout_leaf > sizeof(unsigned long) * 8) {
+ WARN_ON(1);
+ return;
+ }
+
+ /*
* Compute number of nodes that can be handled an rcu_node tree
* with the given number of levels. Setting rcu_capacity[0] makes
* some of the arithmetic easier.
@@ -4117,19 +4130,11 @@ static void __init rcu_init_geometry(void)
rcu_capacity[i] = rcu_capacity[i - 1] * RCU_FANOUT;
/*
- * The boot-time rcu_fanout_leaf parameter is only permitted
- * to increase the leaf-level fanout, not decrease it. Of course,
- * the leaf-level fanout cannot exceed the number of bits in
- * the rcu_node masks. Finally, the tree must be able to accommodate
- * the configured number of CPUs. Complain and fall back to the
- * compile-time values if these limits are exceeded.
+ * The tree must be able to accommodate the configured number of CPUs.
+ * If this limit is exceeded than we have a serious problem elsewhere.
*/
- if (rcu_fanout_leaf < RCU_FANOUT_LEAF ||
- rcu_fanout_leaf > sizeof(unsigned long) * 8 ||
- n > rcu_capacity[MAX_RCU_LVLS]) {
- WARN_ON(1);
- return;
- }
+ if (n > rcu_capacity[MAX_RCU_LVLS])
+ panic("rcu_init_geometry: rcu_capacity[] is too small");
/* Calculate the number of rcu_nodes at each level of the tree. */
for (i = 1; i <= MAX_RCU_LVLS; i++)
--
1.8.1.5
--
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 07/12] rcu: Limit rcu_capacity[] size to RCU_NUM_LVLS items |
| Message-ID | <pNmsr-2cc-41@gated-at.bofh.it> |
| In reply to | #1187261 |
From: Alexander Gordeev <agordeev@redhat.com>
Number of items in rcu_capacity[] array is defined by macro
MAX_RCU_LVLS. However, that array is never accessed beyond
RCU_NUM_LVLS index. Therefore, we can limit the array to
RCU_NUM_LVLS items and eliminate MAX_RCU_LVLS. As result,
in most cases the memory is conserved.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 12 ++++++------
kernel/rcu/tree.h | 2 --
2 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 2103beedb49f..2ec7b796f660 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3998,19 +3998,19 @@ static void __init rcu_init_one(struct rcu_state *rsp,
"rcu_node_0",
"rcu_node_1",
"rcu_node_2",
- "rcu_node_3" }; /* Match MAX_RCU_LVLS */
+ "rcu_node_3" };
static const char * const fqs[] = {
"rcu_node_fqs_0",
"rcu_node_fqs_1",
"rcu_node_fqs_2",
- "rcu_node_fqs_3" }; /* Match MAX_RCU_LVLS */
+ "rcu_node_fqs_3" };
static u8 fl_mask = 0x1;
int cpustride = 1;
int i;
int j;
struct rcu_node *rnp;
- BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */
+ BUILD_BUG_ON(RCU_NUM_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */
/* Silence gcc 4.8 false positive about array index out of range. */
if (rcu_num_lvls <= 0 || rcu_num_lvls > RCU_NUM_LVLS)
@@ -4082,7 +4082,7 @@ static void __init rcu_init_geometry(void)
{
ulong d;
int i;
- int rcu_capacity[MAX_RCU_LVLS];
+ int rcu_capacity[RCU_NUM_LVLS];
/*
* Initialize any unspecified boot parameters.
@@ -4122,14 +4122,14 @@ static void __init rcu_init_geometry(void)
* with the given number of levels.
*/
rcu_capacity[0] = rcu_fanout_leaf;
- for (i = 1; i < MAX_RCU_LVLS; i++)
+ for (i = 1; i < RCU_NUM_LVLS; i++)
rcu_capacity[i] = rcu_capacity[i - 1] * RCU_FANOUT;
/*
* The tree must be able to accommodate the configured number of CPUs.
* If this limit is exceeded than we have a serious problem elsewhere.
*/
- if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS - 1])
+ if (nr_cpu_ids > rcu_capacity[RCU_NUM_LVLS - 1])
panic("rcu_init_geometry: rcu_capacity[] is too small");
/* Calculate the number of levels in the tree. */
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index a6faae53ea8f..d625e9ff0faf 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -36,8 +36,6 @@
* Of course, your mileage may vary.
*/
-#define MAX_RCU_LVLS 4
-
#ifdef CONFIG_RCU_FANOUT
#define RCU_FANOUT CONFIG_RCU_FANOUT
#else /* #ifdef CONFIG_RCU_FANOUT */
--
1.8.1.5
--
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| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Date | 2015-07-18 00:40 +0200 |
| Subject | [PATCH tip/core/rcu 06/12] rcu: Limit rcu_state::levelcnt[] to RCU_NUM_LVLS items |
| Message-ID | <pNmsr-2cc-43@gated-at.bofh.it> |
| In reply to | #1187261 |
From: Alexander Gordeev <agordeev@redhat.com>
Variable rcu_num_lvls is limited by RCU_NUM_LVLS macro.
In turn, rcu_state::levelcnt[] array is never accessed
beyond rcu_num_lvls. Thus, rcu_state::levelcnt[] is safe
to limit to RCU_NUM_LVLS items.
Since rcu_num_lvls could be changed during boot (as result
of rcutree.rcu_fanout_leaf kernel parameter update) one might
assume a new value could overflow the value of RCU_NUM_LVLS.
However, that is not the case, since leaf-level fanout is only
permitted to increase, resulting in rcu_num_lvls possibly to
decrease.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index f1f4784f9107..a6faae53ea8f 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -443,7 +443,7 @@ do { \
struct rcu_state {
struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
- u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
+ u32 levelcnt[RCU_NUM_LVLS]; /* # nodes in each level. */
u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
u8 flavor_mask; /* bit in flavor mask. */
struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
--
1.8.1.5
--
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