From 7b959fc582741227a1c4cba710d6aff8fb183128 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Wed, 22 May 2013 18:34:09 +0900 Subject: kprobes: Fix to free gone and unused optprobes Fix to free gone and unused optprobes. This bug will cause a kernel panic if the user reuses the killed and unused probe. Reported at: http://sourceware.org/ml/systemtap/2013-q2/msg00142.html In the normal path, an optprobe on an init function is unregistered when a module goes live. unregister_kprobe(kp) -> __unregister_kprobe_top ->__disable_kprobe ->disarm_kprobe(ap == op) ->__disarm_kprobe ->unoptimize_kprobe : the op is queued on unoptimizing_list and do nothing in __unregister_kprobe_bottom After a while (usually wait 5 jiffies), kprobe_optimizer runs to unoptimize and free optprobe. kprobe_optimizer ->do_unoptimize_kprobes ->arch_unoptimize_kprobes : moved to free_list ->do_free_cleaned_kprobes ->hlist_del: the op is removed ->free_aggr_kprobe ->arch_remove_optimized_kprobe ->arch_remove_kprobe ->kfree: the op is freed Here, if kprobes_module_callback is called and the delayed unoptimizing probe is picked BEFORE kprobe_optimizer runs, kprobes_module_callback ->kill_kprobe ->kill_optimized_kprobe : dequeued from unoptimizing_list <=!!! ->arch_remove_optimized_kprobe ->arch_remove_kprobe (but op is not freed, and on the kprobe hash table) This doesn't happen if the probe unregistration is done AFTER kprobes_module_callback is called (because at that time the op is gone), and kprobe-tracer does it. To fix this bug, this patch changes kprobes_module_callback to enqueue the op to freeing_list at kill_optimized_kprobe only if the op is unused. The unused probes on freeing_list will be freed in do_free_cleaned_kprobes. Note that this calls arch_remove_*kprobe twice on the same probe. Thus those functions have to check the double free. Fortunately, most of arch codes already checked that except for mips. This will be fixed in the next patch. Signed-off-by: Masami Hiramatsu Cc: Timo Juhani Lindfors Cc: Ananth N Mavinakayanahalli Cc: Anil S Keshavamurthy Cc: Frank Ch. Eigler Cc: systemtap@sourceware.org Cc: yrl.pp-manager.tt@hitachi.com Cc: David S. Miller Cc: "David S. Miller" Link: http://lkml.kernel.org/r/20130522093409.9084.63554.stgit@mhiramat-M0-7522 [ Minor edits. ] Signed-off-by: Ingo Molnar --- kernel/kprobes.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) (limited to 'kernel') diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 3fed7f0cbcd..bddf3b201a4 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -467,6 +467,7 @@ static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr) /* Optimization staging list, protected by kprobe_mutex */ static LIST_HEAD(optimizing_list); static LIST_HEAD(unoptimizing_list); +static LIST_HEAD(freeing_list); static void kprobe_optimizer(struct work_struct *work); static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer); @@ -504,7 +505,7 @@ static __kprobes void do_optimize_kprobes(void) * Unoptimize (replace a jump with a breakpoint and remove the breakpoint * if need) kprobes listed on unoptimizing_list. */ -static __kprobes void do_unoptimize_kprobes(struct list_head *free_list) +static __kprobes void do_unoptimize_kprobes(void) { struct optimized_kprobe *op, *tmp; @@ -515,9 +516,9 @@ static __kprobes void do_unoptimize_kprobes(struct list_head *free_list) /* Ditto to do_optimize_kprobes */ get_online_cpus(); mutex_lock(&text_mutex); - arch_unoptimize_kprobes(&unoptimizing_list, free_list); + arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list); /* Loop free_list for disarming */ - list_for_each_entry_safe(op, tmp, free_list, list) { + list_for_each_entry_safe(op, tmp, &freeing_list, list) { /* Disarm probes if marked disabled */ if (kprobe_disabled(&op->kp)) arch_disarm_kprobe(&op->kp); @@ -536,11 +537,11 @@ static __kprobes void do_unoptimize_kprobes(struct list_head *free_list) } /* Reclaim all kprobes on the free_list */ -static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list) +static __kprobes void do_free_cleaned_kprobes(void) { struct optimized_kprobe *op, *tmp; - list_for_each_entry_safe(op, tmp, free_list, list) { + list_for_each_entry_safe(op, tmp, &freeing_list, list) { BUG_ON(!kprobe_unused(&op->kp)); list_del_init(&op->list); free_aggr_kprobe(&op->kp); @@ -556,8 +557,6 @@ static __kprobes void kick_kprobe_optimizer(void) /* Kprobe jump optimizer */ static __kprobes void kprobe_optimizer(struct work_struct *work) { - LIST_HEAD(free_list); - mutex_lock(&kprobe_mutex); /* Lock modules while optimizing kprobes */ mutex_lock(&module_mutex); @@ -566,7 +565,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) * kprobes before waiting for quiesence period. */ - do_unoptimize_kprobes(&free_list); + do_unoptimize_kprobes(); /* * Step 2: Wait for quiesence period to ensure all running interrupts @@ -581,7 +580,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) do_optimize_kprobes(); /* Step 4: Free cleaned kprobes after quiesence period */ - do_free_cleaned_kprobes(&free_list); + do_free_cleaned_kprobes(); mutex_unlock(&module_mutex); mutex_unlock(&kprobe_mutex); @@ -723,8 +722,19 @@ static void __kprobes kill_optimized_kprobe(struct kprobe *p) if (!list_empty(&op->list)) /* Dequeue from the (un)optimization queue */ list_del_init(&op->list); - op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; + + if (kprobe_unused(p)) { + /* Enqueue if it is unused */ + list_add(&op->list, &freeing_list); + /* + * Remove unused probes from the hash list. After waiting + * for synchronization, this probe is reclaimed. + * (reclaiming is done by do_free_cleaned_kprobes().) + */ + hlist_del_rcu(&op->kp.hlist); + } + /* Don't touch the code, because it is already freed. */ arch_remove_optimized_kprobe(op); } -- cgit v1.2.3 From 26cb63ad11e04047a64309362674bcbbd6a6f246 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 28 May 2013 10:55:48 +0200 Subject: perf: Fix perf mmap bugs Vince reported a problem found by his perf specific trinity fuzzer. Al noticed 2 problems with perf's mmap(): - it has issues against fork() since we use vma->vm_mm for accounting. - it has an rb refcount leak on double mmap(). We fix the issues against fork() by using VM_DONTCOPY; I don't think there's code out there that uses this; we didn't hear about weird accounting problems/crashes. If we do need this to work, the previously proposed VM_PINNED could make this work. Aside from the rb reference leak spotted by Al, Vince's example prog was indeed doing a double mmap() through the use of perf_event_set_output(). This exposes another problem, since we now have 2 events with one buffer, the accounting gets screwy because we account per event. Fix this by making the buffer responsible for its own accounting. Reported-by: Vince Weaver Signed-off-by: Peter Zijlstra Cc: Al Viro Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Link: http://lkml.kernel.org/r/20130528085548.GA12193@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/events/core.c | 37 ++++++++++++++++++++----------------- kernel/events/internal.h | 3 +++ 2 files changed, 23 insertions(+), 17 deletions(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 9dc297faf7c..ae752cd4a08 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2917,7 +2917,7 @@ static void free_event_rcu(struct rcu_head *head) kfree(event); } -static void ring_buffer_put(struct ring_buffer *rb); +static bool ring_buffer_put(struct ring_buffer *rb); static void free_event(struct perf_event *event) { @@ -3582,13 +3582,13 @@ static struct ring_buffer *ring_buffer_get(struct perf_event *event) return rb; } -static void ring_buffer_put(struct ring_buffer *rb) +static bool ring_buffer_put(struct ring_buffer *rb) { struct perf_event *event, *n; unsigned long flags; if (!atomic_dec_and_test(&rb->refcount)) - return; + return false; spin_lock_irqsave(&rb->event_lock, flags); list_for_each_entry_safe(event, n, &rb->event_list, rb_entry) { @@ -3598,6 +3598,7 @@ static void ring_buffer_put(struct ring_buffer *rb) spin_unlock_irqrestore(&rb->event_lock, flags); call_rcu(&rb->rcu_head, rb_free_rcu); + return true; } static void perf_mmap_open(struct vm_area_struct *vma) @@ -3612,18 +3613,20 @@ static void perf_mmap_close(struct vm_area_struct *vma) struct perf_event *event = vma->vm_file->private_data; if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) { - unsigned long size = perf_data_size(event->rb); - struct user_struct *user = event->mmap_user; struct ring_buffer *rb = event->rb; + struct user_struct *mmap_user = rb->mmap_user; + int mmap_locked = rb->mmap_locked; + unsigned long size = perf_data_size(rb); - atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm); - vma->vm_mm->pinned_vm -= event->mmap_locked; rcu_assign_pointer(event->rb, NULL); ring_buffer_detach(event, rb); mutex_unlock(&event->mmap_mutex); - ring_buffer_put(rb); - free_uid(user); + if (ring_buffer_put(rb)) { + atomic_long_sub((size >> PAGE_SHIFT) + 1, &mmap_user->locked_vm); + vma->vm_mm->pinned_vm -= mmap_locked; + free_uid(mmap_user); + } } } @@ -3676,9 +3679,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) WARN_ON_ONCE(event->ctx->parent_ctx); mutex_lock(&event->mmap_mutex); if (event->rb) { - if (event->rb->nr_pages == nr_pages) - atomic_inc(&event->rb->refcount); - else + if (event->rb->nr_pages != nr_pages) ret = -EINVAL; goto unlock; } @@ -3720,12 +3721,14 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) ret = -ENOMEM; goto unlock; } - rcu_assign_pointer(event->rb, rb); + + rb->mmap_locked = extra; + rb->mmap_user = get_current_user(); atomic_long_add(user_extra, &user->locked_vm); - event->mmap_locked = extra; - event->mmap_user = get_current_user(); - vma->vm_mm->pinned_vm += event->mmap_locked; + vma->vm_mm->pinned_vm += extra; + + rcu_assign_pointer(event->rb, rb); perf_event_update_userpage(event); @@ -3734,7 +3737,7 @@ unlock: atomic_inc(&event->mmap_count); mutex_unlock(&event->mmap_mutex); - vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; + vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP; vma->vm_ops = &perf_mmap_vmops; return ret; diff --git a/kernel/events/internal.h b/kernel/events/internal.h index eb675c4d59d..5bc6c8e9b85 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -31,6 +31,9 @@ struct ring_buffer { spinlock_t event_lock; struct list_head event_list; + int mmap_locked; + struct user_struct *mmap_user; + struct perf_event_mmap_page *user_page; void *data_pages[0]; }; -- cgit v1.2.3 From 9bb5d40cd93c9dd4be74834b1dcb1ba03629716b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 4 Jun 2013 10:44:21 +0200 Subject: perf: Fix mmap() accounting hole Vince's fuzzer once again found holes. This time it spotted a leak in the locked page accounting. When an event had redirected output and its close() was the last reference to the buffer we didn't have a vm context to undo accounting. Change the code to destroy the buffer on the last munmap() and detach all redirected events at that time. This provides us the right context to undo the vm accounting. Reported-and-tested-by: Vince Weaver Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20130604084421.GI8923@twins.programming.kicks-ass.net Cc: Signed-off-by: Ingo Molnar --- kernel/events/core.c | 228 ++++++++++++++++++++++++++++++++--------------- kernel/events/internal.h | 3 +- 2 files changed, 159 insertions(+), 72 deletions(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index ae752cd4a08..b391907d535 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -196,9 +196,6 @@ static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx, static void update_context_time(struct perf_event_context *ctx); static u64 perf_event_time(struct perf_event *event); -static void ring_buffer_attach(struct perf_event *event, - struct ring_buffer *rb); - void __weak perf_event_print_debug(void) { } extern __weak const char *perf_pmu_name(void) @@ -2917,7 +2914,8 @@ static void free_event_rcu(struct rcu_head *head) kfree(event); } -static bool ring_buffer_put(struct ring_buffer *rb); +static void ring_buffer_put(struct ring_buffer *rb); +static void ring_buffer_detach(struct perf_event *event, struct ring_buffer *rb); static void free_event(struct perf_event *event) { @@ -2942,15 +2940,30 @@ static void free_event(struct perf_event *event) if (has_branch_stack(event)) { static_key_slow_dec_deferred(&perf_sched_events); /* is system-wide event */ - if (!(event->attach_state & PERF_ATTACH_TASK)) + if (!(event->attach_state & PERF_ATTACH_TASK)) { atomic_dec(&per_cpu(perf_branch_stack_events, event->cpu)); + } } } if (event->rb) { - ring_buffer_put(event->rb); - event->rb = NULL; + struct ring_buffer *rb; + + /* + * Can happen when we close an event with re-directed output. + * + * Since we have a 0 refcount, perf_mmap_close() will skip + * over us; possibly making our ring_buffer_put() the last. + */ + mutex_lock(&event->mmap_mutex); + rb = event->rb; + if (rb) { + rcu_assign_pointer(event->rb, NULL); + ring_buffer_detach(event, rb); + ring_buffer_put(rb); /* could be last */ + } + mutex_unlock(&event->mmap_mutex); } if (is_cgroup_event(event)) @@ -3188,30 +3201,13 @@ static unsigned int perf_poll(struct file *file, poll_table *wait) unsigned int events = POLL_HUP; /* - * Race between perf_event_set_output() and perf_poll(): perf_poll() - * grabs the rb reference but perf_event_set_output() overrides it. - * Here is the timeline for two threads T1, T2: - * t0: T1, rb = rcu_dereference(event->rb) - * t1: T2, old_rb = event->rb - * t2: T2, event->rb = new rb - * t3: T2, ring_buffer_detach(old_rb) - * t4: T1, ring_buffer_attach(rb1) - * t5: T1, poll_wait(event->waitq) - * - * To avoid this problem, we grab mmap_mutex in perf_poll() - * thereby ensuring that the assignment of the new ring buffer - * and the detachment of the old buffer appear atomic to perf_poll() + * Pin the event->rb by taking event->mmap_mutex; otherwise + * perf_event_set_output() can swizzle our rb and make us miss wakeups. */ mutex_lock(&event->mmap_mutex); - - rcu_read_lock(); - rb = rcu_dereference(event->rb); - if (rb) { - ring_buffer_attach(event, rb); + rb = event->rb; + if (rb) events = atomic_xchg(&rb->poll, 0); - } - rcu_read_unlock(); - mutex_unlock(&event->mmap_mutex); poll_wait(file, &event->waitq, wait); @@ -3521,16 +3517,12 @@ static void ring_buffer_attach(struct perf_event *event, return; spin_lock_irqsave(&rb->event_lock, flags); - if (!list_empty(&event->rb_entry)) - goto unlock; - - list_add(&event->rb_entry, &rb->event_list); -unlock: + if (list_empty(&event->rb_entry)) + list_add(&event->rb_entry, &rb->event_list); spin_unlock_irqrestore(&rb->event_lock, flags); } -static void ring_buffer_detach(struct perf_event *event, - struct ring_buffer *rb) +static void ring_buffer_detach(struct perf_event *event, struct ring_buffer *rb) { unsigned long flags; @@ -3549,13 +3541,10 @@ static void ring_buffer_wakeup(struct perf_event *event) rcu_read_lock(); rb = rcu_dereference(event->rb); - if (!rb) - goto unlock; - - list_for_each_entry_rcu(event, &rb->event_list, rb_entry) - wake_up_all(&event->waitq); - -unlock: + if (rb) { + list_for_each_entry_rcu(event, &rb->event_list, rb_entry) + wake_up_all(&event->waitq); + } rcu_read_unlock(); } @@ -3582,23 +3571,14 @@ static struct ring_buffer *ring_buffer_get(struct perf_event *event) return rb; } -static bool ring_buffer_put(struct ring_buffer *rb) +static void ring_buffer_put(struct ring_buffer *rb) { - struct perf_event *event, *n; - unsigned long flags; - if (!atomic_dec_and_test(&rb->refcount)) - return false; + return; - spin_lock_irqsave(&rb->event_lock, flags); - list_for_each_entry_safe(event, n, &rb->event_list, rb_entry) { - list_del_init(&event->rb_entry); - wake_up_all(&event->waitq); - } - spin_unlock_irqrestore(&rb->event_lock, flags); + WARN_ON_ONCE(!list_empty(&rb->event_list)); call_rcu(&rb->rcu_head, rb_free_rcu); - return true; } static void perf_mmap_open(struct vm_area_struct *vma) @@ -3606,28 +3586,100 @@ static void perf_mmap_open(struct vm_area_struct *vma) struct perf_event *event = vma->vm_file->private_data; atomic_inc(&event->mmap_count); + atomic_inc(&event->rb->mmap_count); } +/* + * A buffer can be mmap()ed multiple times; either directly through the same + * event, or through other events by use of perf_event_set_output(). + * + * In order to undo the VM accounting done by perf_mmap() we need to destroy + * the buffer here, where we still have a VM context. This means we need + * to detach all events redirecting to us. + */ static void perf_mmap_close(struct vm_area_struct *vma) { struct perf_event *event = vma->vm_file->private_data; - if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) { - struct ring_buffer *rb = event->rb; - struct user_struct *mmap_user = rb->mmap_user; - int mmap_locked = rb->mmap_locked; - unsigned long size = perf_data_size(rb); + struct ring_buffer *rb = event->rb; + struct user_struct *mmap_user = rb->mmap_user; + int mmap_locked = rb->mmap_locked; + unsigned long size = perf_data_size(rb); - rcu_assign_pointer(event->rb, NULL); - ring_buffer_detach(event, rb); - mutex_unlock(&event->mmap_mutex); + atomic_dec(&rb->mmap_count); + + if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) + return; + + /* Detach current event from the buffer. */ + rcu_assign_pointer(event->rb, NULL); + ring_buffer_detach(event, rb); + mutex_unlock(&event->mmap_mutex); + + /* If there's still other mmap()s of this buffer, we're done. */ + if (atomic_read(&rb->mmap_count)) { + ring_buffer_put(rb); /* can't be last */ + return; + } - if (ring_buffer_put(rb)) { - atomic_long_sub((size >> PAGE_SHIFT) + 1, &mmap_user->locked_vm); - vma->vm_mm->pinned_vm -= mmap_locked; - free_uid(mmap_user); + /* + * No other mmap()s, detach from all other events that might redirect + * into the now unreachable buffer. Somewhat complicated by the + * fact that rb::event_lock otherwise nests inside mmap_mutex. + */ +again: + rcu_read_lock(); + list_for_each_entry_rcu(event, &rb->event_list, rb_entry) { + if (!atomic_long_inc_not_zero(&event->refcount)) { + /* + * This event is en-route to free_event() which will + * detach it and remove it from the list. + */ + continue; } + rcu_read_unlock(); + + mutex_lock(&event->mmap_mutex); + /* + * Check we didn't race with perf_event_set_output() which can + * swizzle the rb from under us while we were waiting to + * acquire mmap_mutex. + * + * If we find a different rb; ignore this event, a next + * iteration will no longer find it on the list. We have to + * still restart the iteration to make sure we're not now + * iterating the wrong list. + */ + if (event->rb == rb) { + rcu_assign_pointer(event->rb, NULL); + ring_buffer_detach(event, rb); + ring_buffer_put(rb); /* can't be last, we still have one */ + } + mutex_unlock(&event->mmap_mutex); + put_event(event); + + /* + * Restart the iteration; either we're on the wrong list or + * destroyed its integrity by doing a deletion. + */ + goto again; } + rcu_read_unlock(); + + /* + * It could be there's still a few 0-ref events on the list; they'll + * get cleaned up by free_event() -- they'll also still have their + * ref on the rb and will free it whenever they are done with it. + * + * Aside from that, this buffer is 'fully' detached and unmapped, + * undo the VM accounting. + */ + + atomic_long_sub((size >> PAGE_SHIFT) + 1, &mmap_user->locked_vm); + vma->vm_mm->pinned_vm -= mmap_locked; + free_uid(mmap_user); + + ring_buffer_put(rb); /* could be last */ } static const struct vm_operations_struct perf_mmap_vmops = { @@ -3677,10 +3729,24 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) return -EINVAL; WARN_ON_ONCE(event->ctx->parent_ctx); +again: mutex_lock(&event->mmap_mutex); if (event->rb) { - if (event->rb->nr_pages != nr_pages) + if (event->rb->nr_pages != nr_pages) { ret = -EINVAL; + goto unlock; + } + + if (!atomic_inc_not_zero(&event->rb->mmap_count)) { + /* + * Raced against perf_mmap_close() through + * perf_event_set_output(). Try again, hope for better + * luck. + */ + mutex_unlock(&event->mmap_mutex); + goto again; + } + goto unlock; } @@ -3722,12 +3788,14 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) goto unlock; } + atomic_set(&rb->mmap_count, 1); rb->mmap_locked = extra; rb->mmap_user = get_current_user(); atomic_long_add(user_extra, &user->locked_vm); vma->vm_mm->pinned_vm += extra; + ring_buffer_attach(event, rb); rcu_assign_pointer(event->rb, rb); perf_event_update_userpage(event); @@ -3737,6 +3805,10 @@ unlock: atomic_inc(&event->mmap_count); mutex_unlock(&event->mmap_mutex); + /* + * Since pinned accounting is per vm we cannot allow fork() to copy our + * vma. + */ vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP; vma->vm_ops = &perf_mmap_vmops; @@ -6415,6 +6487,8 @@ set: if (atomic_read(&event->mmap_count)) goto unlock; + old_rb = event->rb; + if (output_event) { /* get the rb we want to redirect to */ rb = ring_buffer_get(output_event); @@ -6422,16 +6496,28 @@ set: goto unlock; } - old_rb = event->rb; - rcu_assign_pointer(event->rb, rb); if (old_rb) ring_buffer_detach(event, old_rb); + + if (rb) + ring_buffer_attach(event, rb); + + rcu_assign_pointer(event->rb, rb); + + if (old_rb) { + ring_buffer_put(old_rb); + /* + * Since we detached before setting the new rb, so that we + * could attach the new rb, we could have missed a wakeup. + * Provide it now. + */ + wake_up_all(&event->waitq); + } + ret = 0; unlock: mutex_unlock(&event->mmap_mutex); - if (old_rb) - ring_buffer_put(old_rb); out: return ret; } diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 5bc6c8e9b85..ca6599723be 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -31,7 +31,8 @@ struct ring_buffer { spinlock_t event_lock; struct list_head event_list; - int mmap_locked; + atomic_t mmap_count; + unsigned long mmap_locked; struct user_struct *mmap_user; struct perf_event_mmap_page *user_page; -- cgit v1.2.3