From: Andy Adamson <andros@xxxxxxxxxx>
The rsc cache code operates in a read_lock/write_lock environment.
Changes to a cache entry should use the provided rsc_update
routine which takes the write_lock.
The current code sets the expiry_time and the CACHE_NEGATIVE flag
without taking the write_lock as it does not call rsc_update.
Without this patch, while cache_clean sees the entries to be
removed, it does not remove the rsc_entries. This is because
rsc_update sets other fields in the entry to properly trigger
cache_clean.
Cache_clean takes the write_lock to remove expired or invalid
entries from the cache_list and calls cache_put on the entry.
Looking at sunrpc_cache_update, what we want is to invalidate the
cache entry, so that it is direclty replaced which means that
update_rsc is called. We pass in a new zero'ed rsc cache entry
to rsc_update with an expiry_time set to 0 along with the
invalidatedcache entry to be destroyed.
The cache_put at the end of svcauth_gss_accept processing drops
the reference count to 1 which allows the cache_put called by
cache_clean to result in a call to rsc_put and rsc_free
to reap the entry after it has been removed from the cache_list
under the write_lock.
Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
---
net/sunrpc/auth_gss/svcauth_gss.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 45662d7..b8093da 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1409,7 +1409,9 @@ static void destroy_use_gss_proxy_proc_entry(struct net *net) {}
u32 crlen;
struct gss_svc_data *svcdata = rqstp->rq_auth_data;
struct rpc_gss_wire_cred *gc;
- struct rsc *rsci = NULL;
+ struct rsc *rsci = NULL, new = {
+ .mechctx = 0,
+ };
__be32 *rpcstart;
__be32 *reject_stat = resv->iov_base + resv->iov_len;
int ret;
@@ -1489,10 +1491,20 @@ static void destroy_use_gss_proxy_proc_entry(struct net *net) {}
case RPC_GSS_PROC_DESTROY:
if (gss_write_verf(rqstp, rsci->mechctx, gc->gc_seq))
goto auth_err;
- rsci->h.expiry_time = get_seconds();
- set_bit(CACHE_NEGATIVE, &rsci->h.flags);
+
+ /** Invalidate the cache entry so sunrpc_update_cache
+ * direclty updates rsci. new->h.expiry_time is zero,
+ * so rsci->h.expiry_time will be set to zero and
+ * cache_clean will properly remove rsci.
+ */
+ clear_bit(CACHE_VALID, &rsci->h.flags);
+ rsci = rsc_update(sn->rsc_cache, &new, rsci);
+ if (!rsci)
+ goto drop;
+
if (resv->iov_len + 4 > PAGE_SIZE)
goto drop;
+
svc_putnl(resv, RPC_SUCCESS);
goto complete;
case RPC_GSS_PROC_DATA:
--
1.8.3.1
--
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