linux-kernel - [PATCH v2] Revert "char: pcmcia: cm4000_cs: Replace mdelay with usleep_range in set

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Message-Id: <20221218133400.99581-1-duoming@zju.edu.cn>
Date:   Sun, 18 Dec 2022 21:34:00 +0800
From:   Duoming Zhou <duoming@....edu.cn>
To:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org
Cc:     arnd@...db.de, laforge@...monks.org,
        Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH v2] Revert "char: pcmcia: cm4000_cs: Replace mdelay with usleep_range in set_protocol"

This reverts commit be826ada52f1fcabed5b5217c94609ebf5967211.

The function monitor_card() is a timer handler that runs in an
atomic context, but it calls usleep_range() that can sleep.
As a result, the sleep-in-atomic-context bugs will happen.
The process is shown below:

    (atomic context)
monitor_card()
  set_protocol()
    usleep_range() //sleep

The origin commit c1986ee9bea3 ("[PATCH] New Omnikey Cardman
4000 driver") works fine.

Fixes: be826ada52f1 ("char: pcmcia: cm4000_cs: Replace mdelay with usleep_range in set_protocol")
Signed-off-by: Duoming Zhou <duoming@....edu.cn>
---
Changes in v2:
  - Add comments so that this will not be changed again in the future.

 drivers/char/pcmcia/cm4000_cs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/char/pcmcia/cm4000_cs.c b/drivers/char/pcmcia/cm4000_cs.c
index adaec8fd4b1..e656f42a28a 100644
--- a/drivers/char/pcmcia/cm4000_cs.c
+++ b/drivers/char/pcmcia/cm4000_cs.c
@@ -529,7 +529,8 @@ static int set_protocol(struct cm4000_dev *dev, struct ptsreq *ptsreq)
 			DEBUGP(5, dev, "NumRecBytes is valid\n");
 			break;
 		}
-		usleep_range(10000, 11000);
+		/* can not sleep as this is in atomic context */
+		mdelay(10);
 	}
 	if (i == 100) {
 		DEBUGP(5, dev, "Timeout waiting for NumRecBytes getting "
@@ -549,7 +550,8 @@ static int set_protocol(struct cm4000_dev *dev, struct ptsreq *ptsreq)
 			}
 			break;
 		}
-		usleep_range(10000, 11000);
+		/* can not sleep as this is in atomic context */
+		mdelay(10);
 	}
 
 	/* check whether it is a short PTS reply? */
-- 
2.17.1