diff options
| author | John Stultz | 2022-12-14 23:18:34 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2022-12-31 13:33:07 +0100 |
| commit | e84276c8dd8867690bf20ef2ed613eeaca134dc7 (patch) | |
| tree | ec395f4282cc257732321e2fa4909179160736cd /fs/pstore | |
| parent | d7d99f1a0af0fafbb16123148859759580174e07 (diff) | |
pstore: Switch pmsg_lock to an rt_mutex to avoid priority inversion
[ Upstream commit 76d62f24db07f22ccf9bc18ca793c27d4ebef721 ]
Wei Wang reported seeing priority inversion caused latencies
caused by contention on pmsg_lock, and suggested it be switched
to a rt_mutex.
I was initially hesitant this would help, as the tasks in that
trace all seemed to be SCHED_NORMAL, so the benefit would be
limited to only nice boosting.
However, another similar issue was raised where the priority
inversion was seen did involve a blocked RT task so it is clear
this would be helpful in that case.
Cc: Wei Wang <wvw@google.com>
Cc: Midas Chien<midaschieh@google.com>
Cc: Connor O'Brien <connoro@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: kernel-team@android.com
Fixes: 9d5438f462ab ("pstore: Add pmsg - user-space accessible pstore object")
Reported-by: Wei Wang <wvw@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221214231834.3711880-1-jstultz@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'fs/pstore')
| -rw-r--r-- | fs/pstore/pmsg.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c index d8542ec2f38c..18cf94b597e0 100644 --- a/fs/pstore/pmsg.c +++ b/fs/pstore/pmsg.c @@ -7,9 +7,10 @@ #include <linux/device.h> #include <linux/fs.h> #include <linux/uaccess.h> +#include <linux/rtmutex.h> #include "internal.h" -static DEFINE_MUTEX(pmsg_lock); +static DEFINE_RT_MUTEX(pmsg_lock); static ssize_t write_pmsg(struct file *file, const char __user *buf, size_t count, loff_t *ppos) @@ -28,9 +29,9 @@ static ssize_t write_pmsg(struct file *file, const char __user *buf, if (!access_ok(buf, count)) return -EFAULT; - mutex_lock(&pmsg_lock); + rt_mutex_lock(&pmsg_lock); ret = psinfo->write_user(&record, buf); - mutex_unlock(&pmsg_lock); + rt_mutex_unlock(&pmsg_lock); return ret ? ret : count; } |