This is a note to let you know that I've just added the patch titled
nfsd: make nfsd_stats.th_cnt atomic_t
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-make-nfsd_stats.th_cnt-atomic_t.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8ba0a4c5c7c3e36775a5f0210865404b50d1e3d5
Author: NeilBrown <neilb@xxxxxxx>
Date: Mon Nov 29 15:51:25 2021 +1100
nfsd: make nfsd_stats.th_cnt atomic_t
[ Upstream commit 9b6c8c9bebccd5fb785c306b948c08874a88874d ]
This allows us to move the updates for th_cnt out of the mutex.
This is a step towards reducing mutex coverage in nfsd().
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 141d884fee4f4..32f2c46a38323 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -57,7 +57,7 @@ static __be32 nfsd_init_request(struct svc_rqst *,
/*
* nfsd_mutex protects nn->nfsd_serv -- both the pointer itself and the members
* of the svc_serv struct. In particular, ->sv_nrthreads but also to some
- * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
+ * extent ->sv_temp_socks and ->sv_permsocks.
*
* If (out side the lock) nn->nfsd_serv is non-NULL, then it must point to a
* properly initialised 'struct svc_serv' with ->sv_nrthreads > 0 (unless
@@ -955,8 +955,8 @@ nfsd(void *vrqstp)
allow_signal(SIGINT);
allow_signal(SIGQUIT);
- nfsdstats.th_cnt++;
mutex_unlock(&nfsd_mutex);
+ atomic_inc(&nfsdstats.th_cnt);
set_freezable();
@@ -983,8 +983,8 @@ nfsd(void *vrqstp)
/* Clear signals before calling svc_exit_thread() */
flush_signals(current);
+ atomic_dec(&nfsdstats.th_cnt);
mutex_lock(&nfsd_mutex);
- nfsdstats.th_cnt --;
out:
/* Take an extra ref so that the svc_put in svc_exit_thread()
diff --git a/fs/nfsd/stats.c b/fs/nfsd/stats.c
index 1d3b881e73821..a8c5a02a84f04 100644
--- a/fs/nfsd/stats.c
+++ b/fs/nfsd/stats.c
@@ -45,7 +45,7 @@ static int nfsd_proc_show(struct seq_file *seq, void *v)
percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_IO_WRITE]));
/* thread usage: */
- seq_printf(seq, "th %u 0", nfsdstats.th_cnt);
+ seq_printf(seq, "th %u 0", atomic_read(&nfsdstats.th_cnt));
/* deprecated thread usage histogram stats */
for (i = 0; i < 10; i++)
diff --git a/fs/nfsd/stats.h b/fs/nfsd/stats.h
index 51ecda852e23b..9b43dc3d99913 100644
--- a/fs/nfsd/stats.h
+++ b/fs/nfsd/stats.h
@@ -29,11 +29,9 @@ enum {
struct nfsd_stats {
struct percpu_counter counter[NFSD_STATS_COUNTERS_NUM];
- /* Protected by nfsd_mutex */
- unsigned int th_cnt; /* number of available threads */
+ atomic_t th_cnt; /* number of available threads */
};
-
extern struct nfsd_stats nfsdstats;
extern struct svc_stat nfsd_svcstats;
