From: Shyam Prasad N sprasad@microsoft.com
[ Upstream commit 326a8d04f147e2bf393f6f9cdb74126ee6900607 ]
All the server credits and in-flight info is protected by req_lock. Once the req_lock is held, and we've determined that we have enough credits to continue, this lock cannot be dropped till we've made the changes to credits and in-flight count.
However, we used to drop the lock in order to avoid deadlock with the recent srv_lock. This could cause the checks already made to be invalidated.
Fixed it by moving the server status check to before locking req_lock.
Fixes: d7d7a66aacd6 ("cifs: avoid use of global locks for high contention data") Signed-off-by: Shyam Prasad N sprasad@microsoft.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/cifs/smb2ops.c | 19 ++++++++++--------- fs/cifs/transport.c | 20 ++++++++++---------- 2 files changed, 20 insertions(+), 19 deletions(-)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 5065398665f11..bb41b9bae262d 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -208,6 +208,16 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
spin_lock(&server->req_lock); while (1) { + spin_unlock(&server->req_lock); + + spin_lock(&server->srv_lock); + if (server->tcpStatus == CifsExiting) { + spin_unlock(&server->srv_lock); + return -ENOENT; + } + spin_unlock(&server->srv_lock); + + spin_lock(&server->req_lock); if (server->credits <= 0) { spin_unlock(&server->req_lock); cifs_num_waiters_inc(server); @@ -218,15 +228,6 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size, return rc; spin_lock(&server->req_lock); } else { - spin_unlock(&server->req_lock); - spin_lock(&server->srv_lock); - if (server->tcpStatus == CifsExiting) { - spin_unlock(&server->srv_lock); - return -ENOENT; - } - spin_unlock(&server->srv_lock); - - spin_lock(&server->req_lock); scredits = server->credits; /* can deadlock with reopen */ if (scredits <= 8) { diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 24bdd5f4d3bcc..968bfd029b8eb 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -522,6 +522,16 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits, }
while (1) { + spin_unlock(&server->req_lock); + + spin_lock(&server->srv_lock); + if (server->tcpStatus == CifsExiting) { + spin_unlock(&server->srv_lock); + return -ENOENT; + } + spin_unlock(&server->srv_lock); + + spin_lock(&server->req_lock); if (*credits < num_credits) { scredits = *credits; spin_unlock(&server->req_lock); @@ -547,15 +557,6 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits, return -ERESTARTSYS; spin_lock(&server->req_lock); } else { - spin_unlock(&server->req_lock); - - spin_lock(&server->srv_lock); - if (server->tcpStatus == CifsExiting) { - spin_unlock(&server->srv_lock); - return -ENOENT; - } - spin_unlock(&server->srv_lock); - /* * For normal commands, reserve the last MAX_COMPOUND * credits to compound requests. @@ -569,7 +570,6 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits, * for servers that are slow to hand out credits on * new sessions. */ - spin_lock(&server->req_lock); if (!optype && num_credits == 1 && server->in_flight > 2 * MAX_COMPOUND && *credits <= MAX_COMPOUND) {