linux-kernel - [PATCH AUTOSEL 6.1 09/15] cifs: add a warning when the in-flight count goes negative

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Message-Id: <20230626215031.179159-9-sashal@kernel.org>
Date:   Mon, 26 Jun 2023 17:50:25 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Shyam Prasad N <sprasad@...rosoft.com>,
        Bharath SM <bharathsm@...rosoft.com>,
        Steve French <stfrench@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>, pc@....nz,
        lsahlber@...hat.com, dhowells@...hat.com, ematsumiya@...e.de,
        pc@...guebit.com, vl@...ba.org
Subject: [PATCH AUTOSEL 6.1 09/15] cifs: add a warning when the in-flight count goes negative

From: Shyam Prasad N <sprasad@...rosoft.com>

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

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 4fd377185c2ca..d5586f731dbc3 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -93,6 +93,7 @@ smb2_add_credits(struct TCP_Server_Info *server,
 					    server->conn_id, server->hostname, *val,
 					    add, server->in_flight);
 	}
+	WARN_ON_ONCE(server->in_flight == 0);
 	server->in_flight--;
 	if (server->in_flight == 0 &&
 	   ((optype & CIFS_OP_MASK) != CIFS_NEG_OP) &&
-- 
2.39.2