From 9fb981a86ae5008f05018e6ecff052b2ea9daecc Mon Sep 17 00:00:00 2001 From: Shyam Prasad N Date: Thu, 22 Jun 2023 18:16:04 +0000 Subject: [PATCH] cifs: do all necessary checks for credits within or before locking [ 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 Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/smb/client/smb2ops.c | 19 ++++++++++--------- fs/smb/client/transport.c | 20 ++++++++++---------- 2 files changed, 20 insertions(+), 19 deletions(-) diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index d512440..e6a191a 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/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/smb/client/transport.c b/fs/smb/client/transport.c index c961b90..e03ffcf 100644 --- a/fs/smb/client/transport.c +++ b/fs/smb/client/transport.c @@ -549,6 +549,16 @@ 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); @@ -574,15 +584,6 @@ 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. @@ -596,7 +597,6 @@ 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) { -- 2.7.4