linux-kernel - [PATCH AUTOSEL 5.0 31/34] i2c: designware: ratelimit 'transfer when suspended' errors

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Date:   Thu, 16 May 2019 07:39:28 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Wolfram Sang <wsa+renesas@...g-engineering.com>,
        skidnik <skidnik@...il.com>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Sasha Levin <sashal@...nel.org>, linux-i2c@...r.kernel.org
Subject: [PATCH AUTOSEL 5.0 31/34] i2c: designware: ratelimit 'transfer when suspended' errors

From: Wolfram Sang <wsa+renesas@...g-engineering.com>

[ Upstream commit 6bac9bc273cdab6157ad7a2ead09400aabfc445b ]

There are two problems with dev_err() here. One: It is not ratelimited.
Two: We don't see which driver tried to transfer something with a
suspended adapter. Switch to dev_WARN_ONCE to fix both issues. Drawback
is that we don't see if multiple drivers are trying to transfer while
suspended. They need to be discovered one after the other now. This is
better than a high CPU load because a really broken driver might try to
resend endlessly.

Link: https://bugs.archlinux.org/task/62391
Fixes: 275154155538 ("i2c: designware: Do not allow i2c_dw_xfer() calls while suspended")
Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
Reported-by: skidnik <skidnik@...il.com>
Acked-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Tested-by: skidnik <skidnik@...il.com>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/i2c/busses/i2c-designware-master.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index bb8e3f1499796..d464799e40a30 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -426,8 +426,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
 	pm_runtime_get_sync(dev->dev);
 
-	if (dev->suspended) {
-		dev_err(dev->dev, "Error %s call while suspended\n", __func__);
+	if (dev_WARN_ONCE(dev->dev, dev->suspended, "Transfer while suspended\n")) {
 		ret = -ESHUTDOWN;
 		goto done_nolock;
 	}
-- 
2.20.1