Below race can come, if trace_open and resize of cpu buffer is running parallely on different cpus CPUX CPUY ring_buffer_resize atomic_read(&buffer->resize_disabled) tracing_open tracing_reset_online_cpus ring_buffer_reset_cpu rb_reset_cpu rb_update_pages remove/insert pages resetting pointer This race can cause data abort or some times infinte loop in rb_remove_pages and rb_insert_pages while checking pages for sanity.
Signed-off-by: Gaurav Kohli gkohli@codeaurora.org Cc: stable@vger.kernel.org --- Changes since v0: -Addressed Steven's review comments.
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 93ef0ab..15bf28b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4866,6 +4866,9 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu) if (!cpumask_test_cpu(cpu, buffer->cpumask)) return;
+ /* prevent another thread from changing buffer sizes */ + mutex_lock(&buffer->mutex); + atomic_inc(&cpu_buffer->resize_disabled); atomic_inc(&cpu_buffer->record_disabled);
@@ -4876,6 +4879,8 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled); + + mutex_unlock(&buffer->mutex); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
@@ -4889,6 +4894,9 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) struct ring_buffer_per_cpu *cpu_buffer; int cpu;
+ /* prevent another thread from changing buffer sizes */ + mutex_lock(&buffer->mutex); + for_each_online_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu];
@@ -4907,6 +4915,8 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled); } + + mutex_unlock(&buffer->mutex); }
/**
Hi Steven,
please let us know, if below looks good to you or need modifications.
Thanks Gaurav
On 9/24/2020 7:25 PM, Gaurav Kohli wrote:
Below race can come, if trace_open and resize of cpu buffer is running parallely on different cpus CPUX CPUY ring_buffer_resize atomic_read(&buffer->resize_disabled) tracing_open tracing_reset_online_cpus ring_buffer_reset_cpu rb_reset_cpu rb_update_pages remove/insert pages resetting pointer This race can cause data abort or some times infinte loop in rb_remove_pages and rb_insert_pages while checking pages for sanity.
Signed-off-by: Gaurav Kohli gkohli@codeaurora.org Cc: stable@vger.kernel.org
Changes since v0: -Addressed Steven's review comments.
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 93ef0ab..15bf28b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4866,6 +4866,9 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu) if (!cpumask_test_cpu(cpu, buffer->cpumask)) return;
- /* prevent another thread from changing buffer sizes */
- mutex_lock(&buffer->mutex);
- atomic_inc(&cpu_buffer->resize_disabled); atomic_inc(&cpu_buffer->record_disabled);
@@ -4876,6 +4879,8 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu) atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled);
- mutex_unlock(&buffer->mutex); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
@@ -4889,6 +4894,9 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) struct ring_buffer_per_cpu *cpu_buffer; int cpu;
- /* prevent another thread from changing buffer sizes */
- mutex_lock(&buffer->mutex);
- for_each_online_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu];
@@ -4907,6 +4915,8 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled); }
- mutex_unlock(&buffer->mutex); }
/**
On Mon, 5 Oct 2020 10:09:34 +0530 Gaurav Kohli gkohli@codeaurora.org wrote:
Hi Steven,
please let us know, if below looks good to you or need modifications.
Strange, I don't have your original email in my inbox. I do have it in my LKML folder, but that's way too big for me to read. I checked my server logs. I found where I received this from LKML, but there's no log that I received this directly.
How are you sending out your patches? If it doesn't land in my inbox, I'll never see it.
-- Steve
On Mon, 5 Oct 2020 10:25:15 -0400 Steven Rostedt rostedt@goodmis.org wrote:
On Mon, 5 Oct 2020 10:09:34 +0530 Gaurav Kohli gkohli@codeaurora.org wrote:
Hi Steven,
please let us know, if below looks good to you or need modifications.
Strange, I don't have your original email in my inbox. I do have it in my LKML folder, but that's way too big for me to read. I checked my server logs. I found where I received this from LKML, but there's no log that I received this directly.
How are you sending out your patches? If it doesn't land in my inbox, I'll never see it.
BTW, this is the second time this has happened to me. The first time I assumed it may have been me accidentally deleting it. Now I'm thinking it's on your end.
I have yet to received a patch from you directly. Last time I had to pull it from my LKML folder after you replied to me (letting me know you sent it).
-- Steve
On 10/5/2020 7:57 PM, Steven Rostedt wrote:
On Mon, 5 Oct 2020 10:25:15 -0400 Steven Rostedt rostedt@goodmis.org wrote:
On Mon, 5 Oct 2020 10:09:34 +0530 Gaurav Kohli gkohli@codeaurora.org wrote:
Hi Steven,
please let us know, if below looks good to you or need modifications.
Strange, I don't have your original email in my inbox. I do have it in my LKML folder, but that's way too big for me to read. I checked my server logs. I found where I received this from LKML, but there's no log that I received this directly.
How are you sending out your patches? If it doesn't land in my inbox, I'll never see it.
BTW, this is the second time this has happened to me. The first time I assumed it may have been me accidentally deleting it. Now I'm thinking it's on your end.
I have yet to received a patch from you directly. Last time I had to pull it from my LKML folder after you replied to me (letting me know you sent it).
-- Steve
Hi Steven,
I am using normal git send-email(never saw problem with this), Not sure what is wrong. In my older mail i have kept you in to and rest in cc.
Let me try to resent it.
On Mon, 5 Oct 2020 21:59:02 +0530 Gaurav Kohli gkohli@codeaurora.org wrote:
Hi Steven,
I am using normal git send-email(never saw problem with this), Not sure what is wrong. In my older mail i have kept you in to and rest in cc.
Let me try to resent it.
The Cc is working (I got it in my LKML box), but I don't see any connection in my server. Note, the rostedt@goodmis.org is a server at my home.
-- Steve
On 10/5/2020 10:02 PM, Steven Rostedt wrote:
On Mon, 5 Oct 2020 21:59:02 +0530 Gaurav Kohli gkohli@codeaurora.org wrote:
Hi Steven,
I am using normal git send-email(never saw problem with this), Not sure what is wrong. In my older mail i have kept you in to and rest in cc.
Let me try to resent it.
The Cc is working (I got it in my LKML box), but I don't see any connection in my server. Note, the rostedt@goodmis.org is a server at my home.
-- Steve
Thanks for update, i will verify my account settings and will send my patch tomorrow.
linux-stable-mirror@lists.linaro.org
-
Gaurav Kohli -
Steven Rostedt