6.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: NeilBrown <neilb@xxxxxxx>
[ Upstream commit 60749cbe3d8ae572a6c7dda675de3e8b25797a18 ]
sp_nrthreads is only ever accessed under the service mutex
nlmsvc_mutex nfs_callback_mutex nfsd_mutex
so these is no need for it to be an atomic_t.
The fact that all code using it is single-threaded means that we can
simplify svc_pool_victim and remove the temporary elevation of
sp_nrthreads.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Stable-dep-of: aadc3bbea163 ("NFSD: Limit the number of concurrent async COPY operations")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/nfsd/nfsctl.c | 2 +-
fs/nfsd/nfssvc.c | 2 +-
include/linux/sunrpc/svc.h | 4 ++--
net/sunrpc/svc.c | 31 +++++++++++--------------------
4 files changed, 15 insertions(+), 24 deletions(-)
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 34eb2c2cbcde3..e8704a4e848ca 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1762,7 +1762,7 @@ int nfsd_nl_threads_get_doit(struct sk_buff *skb, struct genl_info *info)
struct svc_pool *sp = &nn->nfsd_serv->sv_pools[i];
err = nla_put_u32(skb, NFSD_A_SERVER_THREADS,
- atomic_read(&sp->sp_nrthreads));
+ sp->sp_nrthreads);
if (err)
goto err_unlock;
}
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 0bc8eaa5e0098..8103c3c90cd11 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -705,7 +705,7 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
if (serv)
for (i = 0; i < serv->sv_nrpools && i < n; i++)
- nthreads[i] = atomic_read(&serv->sv_pools[i].sp_nrthreads);
+ nthreads[i] = serv->sv_pools[i].sp_nrthreads;
return 0;
}
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index a7d0406b9ef59..6811681033c0f 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -33,9 +33,9 @@
* node traffic on multi-node NUMA NFS servers.
*/
struct svc_pool {
- unsigned int sp_id; /* pool id; also node id on NUMA */
+ unsigned int sp_id; /* pool id; also node id on NUMA */
struct lwq sp_xprts; /* pending transports */
- atomic_t sp_nrthreads; /* # of threads in pool */
+ unsigned int sp_nrthreads; /* # of threads in pool */
struct list_head sp_all_threads; /* all server threads */
struct llist_head sp_idle_threads; /* idle server threads */
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 88a59cfa5583c..df06b152ed94e 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -713,7 +713,7 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
serv->sv_nrthreads += 1;
spin_unlock_bh(&serv->sv_lock);
- atomic_inc(&pool->sp_nrthreads);
+ pool->sp_nrthreads += 1;
/* Protected by whatever lock the service uses when calling
* svc_set_num_threads()
@@ -768,31 +768,22 @@ svc_pool_victim(struct svc_serv *serv, struct svc_pool *target_pool,
struct svc_pool *pool;
unsigned int i;
-retry:
pool = target_pool;
- if (pool != NULL) {
- if (atomic_inc_not_zero(&pool->sp_nrthreads))
- goto found_pool;
- return NULL;
- } else {
+ if (!pool) {
for (i = 0; i < serv->sv_nrpools; i++) {
pool = &serv->sv_pools[--(*state) % serv->sv_nrpools];
- if (atomic_inc_not_zero(&pool->sp_nrthreads))
- goto found_pool;
+ if (pool->sp_nrthreads)
+ break;
}
- return NULL;
}
-found_pool:
- set_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
- set_bit(SP_NEED_VICTIM, &pool->sp_flags);
- if (!atomic_dec_and_test(&pool->sp_nrthreads))
+ if (pool && pool->sp_nrthreads) {
+ set_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
+ set_bit(SP_NEED_VICTIM, &pool->sp_flags);
return pool;
- /* Nothing left in this pool any more */
- clear_bit(SP_NEED_VICTIM, &pool->sp_flags);
- clear_bit(SP_VICTIM_REMAINS, &pool->sp_flags);
- goto retry;
+ }
+ return NULL;
}
static int
@@ -871,7 +862,7 @@ svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
if (!pool)
nrservs -= serv->sv_nrthreads;
else
- nrservs -= atomic_read(&pool->sp_nrthreads);
+ nrservs -= pool->sp_nrthreads;
if (nrservs > 0)
return svc_start_kthreads(serv, pool, nrservs);
@@ -959,7 +950,7 @@ svc_exit_thread(struct svc_rqst *rqstp)
list_del_rcu(&rqstp->rq_all);
- atomic_dec(&pool->sp_nrthreads);
+ pool->sp_nrthreads -= 1;
spin_lock_bh(&serv->sv_lock);
serv->sv_nrthreads -= 1;
--
2.43.0
