Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1683051 > unrolled thread

[PATCH 06/15] kernel: convert perf_event_context.refcount from atomic_t to refcount_t

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH 06/15] kernel: convert perf_event_context.refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-07-07 11:10 +0200
    Re: [PATCH 06/15] kernel: convert perf_event_context.refcount from  atomic_t to refcount_t Peter Zijlstra <peterz@infradead.org> - 2017-07-07 11:30 +0200
      RE: [PATCH 06/15] kernel: convert perf_event_context.refcount from  atomic_t to refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-07-07 12:20 +0200

#1683051 — [PATCH 06/15] kernel: convert perf_event_context.refcount from atomic_t to refcount_t

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
 include/linux/perf_event.h |  3 ++-
 kernel/events/core.c       | 12 ++++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index a3b873f..f7a9802 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -54,6 +54,7 @@ struct perf_guest_info_callbacks {
 #include <linux/perf_regs.h>
 #include <linux/workqueue.h>
 #include <linux/cgroup.h>
+#include <linux/refcount.h>
 #include <asm/local.h>
 
 struct perf_callchain_entry {
@@ -750,7 +751,7 @@ struct perf_event_context {
 	int				nr_stat;
 	int				nr_freq;
 	int				rotate_disable;
-	atomic_t			refcount;
+	refcount_t			refcount;
 	struct task_struct		*task;
 
 	/*
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1538df9..11d051f 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1109,7 +1109,7 @@ static void perf_event_ctx_deactivate(struct perf_event_context *ctx)
 
 static void get_ctx(struct perf_event_context *ctx)
 {
-	WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
+	refcount_inc(&ctx->refcount);
 }
 
 static void free_ctx(struct rcu_head *head)
@@ -1123,7 +1123,7 @@ static void free_ctx(struct rcu_head *head)
 
 static void put_ctx(struct perf_event_context *ctx)
 {
-	if (atomic_dec_and_test(&ctx->refcount)) {
+	if (refcount_dec_and_test(&ctx->refcount)) {
 		if (ctx->parent_ctx)
 			put_ctx(ctx->parent_ctx);
 		if (ctx->task && ctx->task != TASK_TOMBSTONE)
@@ -1201,7 +1201,7 @@ perf_event_ctx_lock_nested(struct perf_event *event, int nesting)
 again:
 	rcu_read_lock();
 	ctx = ACCESS_ONCE(event->ctx);
-	if (!atomic_inc_not_zero(&ctx->refcount)) {
+	if (!refcount_inc_not_zero(&ctx->refcount)) {
 		rcu_read_unlock();
 		goto again;
 	}
@@ -1329,7 +1329,7 @@ perf_lock_task_context(struct task_struct *task, int ctxn, unsigned long *flags)
 		}
 
 		if (ctx->task == TASK_TOMBSTONE ||
-		    !atomic_inc_not_zero(&ctx->refcount)) {
+		    !refcount_inc_not_zero(&ctx->refcount)) {
 			raw_spin_unlock(&ctx->lock);
 			ctx = NULL;
 		} else {
@@ -3760,7 +3760,7 @@ static void __perf_event_init_context(struct perf_event_context *ctx)
 	INIT_LIST_HEAD(&ctx->pinned_groups);
 	INIT_LIST_HEAD(&ctx->flexible_groups);
 	INIT_LIST_HEAD(&ctx->event_list);
-	atomic_set(&ctx->refcount, 1);
+	refcount_set(&ctx->refcount, 1);
 }
 
 static struct perf_event_context *
@@ -9791,7 +9791,7 @@ __perf_event_ctx_lock_double(struct perf_event *group_leader,
 again:
 	rcu_read_lock();
 	gctx = READ_ONCE(group_leader->ctx);
-	if (!atomic_inc_not_zero(&gctx->refcount)) {
+	if (!refcount_inc_not_zero(&gctx->refcount)) {
 		rcu_read_unlock();
 		goto again;
 	}
-- 
2.7.4

[toc] | [next] | [standalone]

#1683069 — Re: [PATCH 06/15] kernel: convert perf_event_context.refcount from atomic_t to refcount_t

On Fri, Jul 07, 2017 at 12:04:20PM +0300, Elena Reshetova wrote:
> refcount_t type and corresponding API should be
> used instead of atomic_t when the variable is used as
> a reference counter. This allows to avoid accidental
> refcounter overflows that might lead to use-after-free
> situations.
> 
> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
> Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: David Windsor <dwindsor@gmail.com>

That's an invalid SoB chain.. can't do anything with these patches.

[toc] | [prev] | [next] | [standalone]

#1683104 — RE: [PATCH 06/15] kernel: convert perf_event_context.refcount from atomic_t to refcount_t

 Subject: Re: [PATCH 06/15] kernel: convert perf_event_context.refcount from
> atomic_t to refcount_t
> 
> On Fri, Jul 07, 2017 at 12:04:20PM +0300, Elena Reshetova wrote:
> > refcount_t type and corresponding API should be
> > used instead of atomic_t when the variable is used as
> > a reference counter. This allows to avoid accidental
> > refcounter overflows that might lead to use-after-free
> > situations.
> >
> > Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
> > Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > Signed-off-by: David Windsor <dwindsor@gmail.com>
> 
> That's an invalid SoB chain.. can't do anything with these patches.

OK, will fix. 

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web