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Groups > linux.kernel > #1678085
| From | Todd Kjos <tkjos@android.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 13/37] binder: refactor queue management in binder_thread_read |
| Date | 2017-06-29 21:10 +0200 |
| Message-ID | <tXMZc-354-35@gated-at.bofh.it> (permalink) |
| References | <tXMZb-354-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
In binder_thread_read, the BINDER_WORK_NODE command is used
to communicate the references on the node to userspace. It
can take a couple of iterations in the loop to construct
the list of commands for user space. When locking is added,
the lock would need to be release on each iteration which
means the state could change. The work item is not dequeued
during this process which prevents a simpler queue management
that can just dequeue up front and handle the work item.
Fixed by changing the BINDER_WORK_NODE algorithm in
binder_thread_read to determine which commands to send
to userspace atomically in 1 pass so it stays consistent
with the kernel view.
The work item is now dequeued immediately since only
1 pass is needed.
Signed-off-by: Todd Kjos <tkjos@google.com>
---
drivers/android/binder.c | 151 +++++++++++++++++++++++++++++------------------
1 file changed, 94 insertions(+), 57 deletions(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 62ac0c41b8a6..f17d1dfa5b02 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2285,6 +2285,37 @@ static int binder_has_thread_work(struct binder_thread *thread)
(thread->looper & BINDER_LOOPER_STATE_NEED_RETURN);
}
+static int binder_put_node_cmd(struct binder_proc *proc,
+ struct binder_thread *thread,
+ void __user **ptrp,
+ binder_uintptr_t node_ptr,
+ binder_uintptr_t node_cookie,
+ int node_debug_id,
+ uint32_t cmd, const char *cmd_name)
+{
+ void __user *ptr = *ptrp;
+
+ if (put_user(cmd, (uint32_t __user *)ptr))
+ return -EFAULT;
+ ptr += sizeof(uint32_t);
+
+ if (put_user(node_ptr, (binder_uintptr_t __user *)ptr))
+ return -EFAULT;
+ ptr += sizeof(binder_uintptr_t);
+
+ if (put_user(node_cookie, (binder_uintptr_t __user *)ptr))
+ return -EFAULT;
+ ptr += sizeof(binder_uintptr_t);
+
+ binder_stat_br(proc, thread, cmd);
+ binder_debug(BINDER_DEBUG_USER_REFS, "%d:%d %s %d u%016llx c%016llx\n",
+ proc->pid, thread->pid, cmd_name, node_debug_id,
+ (u64)node_ptr, (u64)node_cookie);
+
+ *ptrp = ptr;
+ return 0;
+}
+
static int binder_thread_read(struct binder_proc *proc,
struct binder_thread *thread,
binder_uintptr_t binder_buffer, size_t size,
@@ -2410,72 +2441,78 @@ static int binder_thread_read(struct binder_proc *proc,
} break;
case BINDER_WORK_NODE: {
struct binder_node *node = container_of(w, struct binder_node, work);
- uint32_t cmd = BR_NOOP;
- const char *cmd_name;
- int strong = node->internal_strong_refs || node->local_strong_refs;
- int weak = !hlist_empty(&node->refs) || node->local_weak_refs || strong;
-
- if (weak && !node->has_weak_ref) {
- cmd = BR_INCREFS;
- cmd_name = "BR_INCREFS";
+ int strong, weak;
+ binder_uintptr_t node_ptr = node->ptr;
+ binder_uintptr_t node_cookie = node->cookie;
+ int node_debug_id = node->debug_id;
+ int has_weak_ref;
+ int has_strong_ref;
+ void __user *orig_ptr = ptr;
+
+ BUG_ON(proc != node->proc);
+ strong = node->internal_strong_refs ||
+ node->local_strong_refs;
+ weak = !hlist_empty(&node->refs) ||
+ node->local_weak_refs || strong;
+ has_strong_ref = node->has_strong_ref;
+ has_weak_ref = node->has_weak_ref;
+
+ if (weak && !has_weak_ref) {
node->has_weak_ref = 1;
node->pending_weak_ref = 1;
node->local_weak_refs++;
- } else if (strong && !node->has_strong_ref) {
- cmd = BR_ACQUIRE;
- cmd_name = "BR_ACQUIRE";
+ }
+ if (strong && !has_strong_ref) {
node->has_strong_ref = 1;
node->pending_strong_ref = 1;
node->local_strong_refs++;
- } else if (!strong && node->has_strong_ref) {
- cmd = BR_RELEASE;
- cmd_name = "BR_RELEASE";
+ }
+ if (!strong && has_strong_ref)
node->has_strong_ref = 0;
- } else if (!weak && node->has_weak_ref) {
- cmd = BR_DECREFS;
- cmd_name = "BR_DECREFS";
+ if (!weak && has_weak_ref)
node->has_weak_ref = 0;
+ list_del(&w->entry);
+
+ if (!weak && !strong) {
+ binder_debug(BINDER_DEBUG_INTERNAL_REFS,
+ "%d:%d node %d u%016llx c%016llx deleted\n",
+ proc->pid, thread->pid,
+ node_debug_id,
+ (u64)node_ptr,
+ (u64)node_cookie);
+ rb_erase(&node->rb_node, &proc->nodes);
+ kfree(node);
+ binder_stats_deleted(BINDER_STAT_NODE);
}
- if (cmd != BR_NOOP) {
- if (put_user(cmd, (uint32_t __user *)ptr))
- return -EFAULT;
- ptr += sizeof(uint32_t);
- if (put_user(node->ptr,
- (binder_uintptr_t __user *)ptr))
- return -EFAULT;
- ptr += sizeof(binder_uintptr_t);
- if (put_user(node->cookie,
- (binder_uintptr_t __user *)ptr))
- return -EFAULT;
- ptr += sizeof(binder_uintptr_t);
-
- binder_stat_br(proc, thread, cmd);
- binder_debug(BINDER_DEBUG_USER_REFS,
- "%d:%d %s %d u%016llx c%016llx\n",
- proc->pid, thread->pid, cmd_name,
- node->debug_id,
- (u64)node->ptr, (u64)node->cookie);
- } else {
- list_del_init(&w->entry);
- if (!weak && !strong) {
- binder_debug(BINDER_DEBUG_INTERNAL_REFS,
- "%d:%d node %d u%016llx c%016llx deleted\n",
- proc->pid, thread->pid,
- node->debug_id,
- (u64)node->ptr,
- (u64)node->cookie);
- rb_erase(&node->rb_node, &proc->nodes);
- kfree(node);
- binder_stats_deleted(BINDER_STAT_NODE);
- } else {
- binder_debug(BINDER_DEBUG_INTERNAL_REFS,
- "%d:%d node %d u%016llx c%016llx state unchanged\n",
- proc->pid, thread->pid,
- node->debug_id,
- (u64)node->ptr,
- (u64)node->cookie);
- }
- }
+ if (weak && !has_weak_ref)
+ ret = binder_put_node_cmd(
+ proc, thread, &ptr, node_ptr,
+ node_cookie, node_debug_id,
+ BR_INCREFS, "BR_INCREFS");
+ if (!ret && strong && !has_strong_ref)
+ ret = binder_put_node_cmd(
+ proc, thread, &ptr, node_ptr,
+ node_cookie, node_debug_id,
+ BR_ACQUIRE, "BR_ACQUIRE");
+ if (!ret && !strong && has_strong_ref)
+ ret = binder_put_node_cmd(
+ proc, thread, &ptr, node_ptr,
+ node_cookie, node_debug_id,
+ BR_RELEASE, "BR_RELEASE");
+ if (!ret && !weak && has_weak_ref)
+ ret = binder_put_node_cmd(
+ proc, thread, &ptr, node_ptr,
+ node_cookie, node_debug_id,
+ BR_DECREFS, "BR_DECREFS");
+ if (orig_ptr == ptr)
+ binder_debug(BINDER_DEBUG_INTERNAL_REFS,
+ "%d:%d node %d u%016llx c%016llx state unchanged\n",
+ proc->pid, thread->pid,
+ node_debug_id,
+ (u64)node_ptr,
+ (u64)node_cookie);
+ if (ret)
+ return ret;
} break;
case BINDER_WORK_DEAD_BINDER:
case BINDER_WORK_DEAD_BINDER_AND_CLEAR:
--
2.13.2.725.g09c95d1e9-goog
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 00/37] fine-grained locking in binder driver Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 30/37] binder: protect proc->nodes with inner lock Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 13/37] binder: refactor queue management in binder_thread_read Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 26/37] binder: introduce locking helper functions Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 18/37] binder: add more debug info when allocation fails. Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 24/37] binder: refactor binder ref inc/dec for thread safety Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 15/37] binder: don't modify thread->looper from other threads Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 22/37] binder: make sure target_node has strong ref Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 27/37] binder: use inner lock to sync work dq and node counts Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 10/37] binder: change binder_stats to atomics Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 36/37] binder: fix death race conditions Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
Re: [PATCH 36/37] binder: fix death race conditions Greg KH <gregkh@linuxfoundation.org> - 2017-06-30 08:10 +0200
[PATCH 19/37] binder: use atomic for transaction_log index Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 03/37] binder: Use wake up hint for synchronous transactions. Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
Re: [PATCH 03/37] binder: Use wake up hint for synchronous transactions. Greg KH <gregkh@linuxfoundation.org> - 2017-07-03 11:20 +0200
[PATCH 33/37] binder: use inner lock to protect thread accounting Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 31/37] binder: protect proc->threads with inner_lock Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 04/37] binder: separate binder allocator structure from binder proc Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 09/37] binder: add protection for non-perf cases Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 37/37] binder: remove global binder lock Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 02/37] binder: use group leader instead of open thread Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
Re: [PATCH 02/37] binder: use group leader instead of open thread Greg KH <gregkh@linuxfoundation.org> - 2017-07-03 11:20 +0200
[PATCH 12/37] binder: add log information for binder transaction failures Todd Kjos <tkjos@android.com> - 2017-06-29 21:10 +0200
[PATCH 08/37] binder: remove binder_debug_no_lock mechanism Todd Kjos <tkjos@android.com> - 2017-06-29 21:20 +0200
[PATCH 17/37] binder: protect against two threads freeing buffer Todd Kjos <tkjos@android.com> - 2017-06-29 21:20 +0200
[PATCH 05/37] binder: remove unneeded cleanup code Todd Kjos <tkjos@android.com> - 2017-06-29 21:20 +0200
[PATCH 21/37] binder: guarantee txn complete / errors delivered in-order Todd Kjos <tkjos@android.com> - 2017-06-29 21:20 +0200
[PATCH 11/37] binder: make binder_last_id an atomic Todd Kjos <tkjos@android.com> - 2017-06-29 21:20 +0200
[PATCH 16/37] binder: remove dead code in binder_get_ref_for_node Todd Kjos <tkjos@android.com> - 2017-06-29 21:20 +0200
[PATCH 14/37] binder: avoid race conditions when enqueuing txn Todd Kjos <tkjos@android.com> - 2017-06-29 21:20 +0200
Re: [PATCH 00/37] fine-grained locking in binder driver Greg KH <gregkh@linuxfoundation.org> - 2017-06-30 08:10 +0200
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