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| author |   Yang Erkun <yangerkun@huawei.com> | 2024-12-25 14:59:07 +0800 |
|---|---|---|
| committer |   Chuck Lever <chuck.lever@oracle.com> | 2025-01-06 09:37:41 -0500 |
| commit | 1b10f0b603c066d81327c163a23c19f01e112366 (patch) | |
| tree | 6a0092e565f9f15a2131b3b84e3709464ce2c4a3 | |
| parent | nfsd: no need get cache ref when protected by rcu (diff) | |
| download | linux-rng-1b10f0b603c066d81327c163a23c19f01e112366.tar.xz linux-rng-1b10f0b603c066d81327c163a23c19f01e112366.zip | |
SUNRPC: no need get cache ref when protected by rcu
rcu_read_lock/rcu_read_unlock has already provide protection for the
pointer we will reference when we call c_show. Therefore, there is no
need to obtain a cache reference to help protect cache_head.
Additionally, the .put such as expkey_put/svc_export_put will invoke
dput, which can sleep and break rcu. Stop get cache reference to fix
them all.
Fixes: ae74136b4bb6 ("SUNRPC: Allow cache lookups to use RCU protection rather than the r/w spinlock")
Suggested-by: NeilBrown <neilb@suse.de>
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
| -rw-r--r-- | net/sunrpc/cache.c | 12 |
1 files changed, 3 insertions, 9 deletions
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 88f42a27c8cc..cb279eb9ac4b 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -1438,17 +1438,11 @@ static int c_show(struct seq_file *m, void *p) seq_printf(m, "# expiry=%lld refcnt=%d flags=%lx\n", convert_to_wallclock(cp->expiry_time), kref_read(&cp->ref), cp->flags); - if (!cache_get_rcu(cp)) - return 0; - if (cache_check(cd, cp, NULL)) - /* cache_check does a cache_put on failure */ + if (cache_check_rcu(cd, cp, NULL)) + seq_puts(m, "# "); + else if (cache_is_expired(cd, cp)) seq_puts(m, "# "); - else { - if (cache_is_expired(cd, cp)) - seq_puts(m, "# "); - cache_put(cp, cd); - } return cd->cache_show(m, cd, cp); } |