From: Shyam Prasad N <sprasad@microsoft.com>
Date: Fri, 9 Jun 2023 17:46:56 +0000 (+0000)
Subject: cifs: add a warning when the in-flight count goes negative
X-Git-Tag: v4.14.326~158
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=997f3b2db5cdc9799e7f2efedbc78562a3150999;p=thirdparty%2Fkernel%2Fstable.git

cifs: add a warning when the in-flight count goes negative

[ Upstream commit e4645cc2f1e2d6f268bb8dcfac40997c52432aed ]

We've seen the in-flight count go into negative with some
internal stress testing in Microsoft.

Adding a WARN when this happens, in hope of understanding
why this happens when it happens.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index dec306a3b0f41..3287795c648e5 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -78,6 +78,7 @@ smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add,
 		*val = 65000; /* Don't get near 64K credits, avoid srv bugs */
 		printk_once(KERN_WARNING "server overflowed SMB3 credits\n");
 	}
+	WARN_ON_ONCE(server->in_flight == 0);
 	server->in_flight--;
 	if (server->in_flight == 0 && (optype & CIFS_OP_MASK) != CIFS_NEG_OP)
 		rc = change_conf(server);