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authorShiju Jose <shiju.jose@huawei.com>2023-02-02 21:23:09 +0300
committerSteven Rostedt (Google) <rostedt@goodmis.org>2023-02-03 00:15:53 +0300
commit3e46d910d8acf94e5360126593b68bf4fee4c4a1 (patch)
treed379a85f23fb4dd0095ff1375bc0c2bb0c2e7e15 /kernel
parent78020233418518faa72fba11f40e1d53b9e88a2e (diff)
downloadlinux-3e46d910d8acf94e5360126593b68bf4fee4c4a1.tar.xz
tracing: Fix poll() and select() do not work on per_cpu trace_pipe and trace_pipe_raw
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. Link: https://lore.kernel.org/linux-trace-kernel/20230202182309.742-2-shiju.jose@huawei.com Cc: <mhiramat@kernel.org> Cc: <mchehab@kernel.org> Cc: <linux-edac@vger.kernel.org> Cc: stable@vger.kernel.org Fixes: 42fb0a1e84ff5 ("tracing/ring-buffer: Have polling block on watermark") Signed-off-by: Shiju Jose <shiju.jose@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c3
1 files changed, 0 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 78ed5f1baa8c..c9e40f692650 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)++;