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SUNRPC: no need get cache ref when protected by rcu

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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: ae74136b4b ("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>
This commit is contained in:
Yang Erkun
2024-12-25 14:59:07 +08:00
committed by Chuck Lever
parent c224edca7a
commit 1b10f0b603
1 changed files with 3 additions and 9 deletions
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12
net/sunrpc/cache.c
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@@ -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);
}