| Message ID | 20230202182309.742-2-shiju.jose@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RFC,1/1] tracing: Fix poll() and select() do not work on per_cpu trace_pipe and trace_pipe_raw | expand |
On Thu, 2 Feb 2023 18:23:09 +0000 <shiju.jose@huawei.com> wrote: > From: Shiju Jose <shiju.jose@huawei.com> > > poll() and select() on per_cpu trace_pipe and trace_pipe_raw do not work > since kernel 6.1-rc6. This issue is seen after the commit > 42fb0a1e84ff525ebe560e2baf9451ab69127e2b ("tracing/ring-buffer: Have > polling block on watermark"). > > This issue is firstly detected and reported, when testing the CXL error > events in the rasdaemon and also erified using the test application for poll() > and select(). > > This issue occurs for the per_cpu case, when calling the ring_buffer_poll_wait(), > in kernel/trace/ring_buffer.c, with the buffer_percent > 0 and then wait until the > percentage of pages are available. The default value set for the buffer_percent is 50 > in the kernel/trace/trace.c. > > As a fix, allow userspace application could set buffer_percent as 0 through > the buffer_percent_fops, so that the task will wake up as soon as data is added > to any of the specific cpu buffer. > > Fixes: 42fb0a1e84ff5 ("tracing/ring-buffer: Have polling block on watermark") > Signed-off-by: Shiju Jose <shiju.jose@huawei.com> > --- This makes sense to me. I'm going to run a bunch of tests on this and see if anything else breaks. Thanks! -- Steve > kernel/trace/trace.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index a555a861b978..01164c78483a 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -9148,9 +9148,6 @@ buffer_percent_write(struct file *filp, const char __user *ubuf, > if (val > 100) > return -EINVAL; > > - if (!val) > - val = 1; > - > tr->buffer_percent = val; > > (*ppos)++;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a555a861b978..01164c78483a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9148,9 +9148,6 @@ buffer_percent_write(struct file *filp, const char __user *ubuf, if (val > 100) return -EINVAL; - if (!val) - val = 1; - tr->buffer_percent = val; (*ppos)++;