[PATCH AUTOSEL 5.15 5/9] cifs: add a warning when the in-flight count goes negative

[Sasha Levin]

From: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Reviewed-by: Bharath SM <bharathsm@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/cifs/smb2ops.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 560c4ababfe1a..fe96e2afeea61 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -85,6 +85,7 @@ smb2_add_credits(struct TCP_Server_Info *server,
 		*val = 65000; /* Don't get near 64K credits, avoid srv bugs */
 		pr_warn_once("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) &&
-- 
2.40.1