linux-kernel - [PATCH] scsi: wd719x: Fix sleeping under a spinlock

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Date:   Wed, 5 Dec 2018 12:21:44 +0800
From:   Wen Yang <wen.yang99@....com.cn>
To:     jejb@...ux.ibm.com, martin.petersen@...cle.com
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        zhong.weidong@....com.cn, Wen Yang <wen.yang99@....com.cn>
Subject: [PATCH] scsi: wd719x: Fix sleeping under a spinlock

Currently, dma_alloc_coherent is being called with a GFP_KERNEL
flag which allows it to sleep with a spinlock held.
The call tree is:
wd719x_host_reset() holds wd->sh->host_lock
    -> wd719x_chip_init()
        -> dma_alloc_coherent() uses GFP_KERNEL

This patch introduces a can_sleep parameter into
the wd719x_chip_init() function. When we have spinlock and
can't sleep, we pass in 0; in other cases, we pass in 1.

Signed-off-by: Wen Yang <wen.yang99@....com.cn>
CC: "James E.J. Bottomley" <jejb@...ux.ibm.com>
CC: "Martin K. Petersen" <martin.petersen@...cle.com>
CC: linux-scsi@...r.kernel.org
CC: linux-kernel@...r.kernel.org
---
 drivers/scsi/wd719x.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/wd719x.c b/drivers/scsi/wd719x.c
index 808ba8e952db..e1dac0115947 100644
--- a/drivers/scsi/wd719x.c
+++ b/drivers/scsi/wd719x.c
@@ -289,7 +289,7 @@ static int wd719x_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *cmd)
 	return 0;
 }
 
-static int wd719x_chip_init(struct wd719x *wd)
+static int wd719x_chip_init(struct wd719x *wd, int can_sleep)
 {
 	int i, ret;
 	u32 risc_init[3];
@@ -318,7 +318,8 @@ static int wd719x_chip_init(struct wd719x *wd)
 
 	if (!wd->fw_virt)
 		wd->fw_virt = dma_alloc_coherent(&wd->pdev->dev, wd->fw_size,
-						 &wd->fw_phys, GFP_KERNEL);
+						 &wd->fw_phys, can_sleep ?
+						 GFP_KERNEL : GFP_ATOMIC);
 	if (!wd->fw_virt) {
 		ret = -ENOMEM;
 		goto wd719x_init_end;
@@ -510,7 +511,7 @@ static int wd719x_host_reset(struct scsi_cmnd *cmd)
 	dev_info(&wd->pdev->dev, "host reset requested\n");
 	spin_lock_irqsave(wd->sh->host_lock, flags);
 	/* Try to reinit the RISC */
-	if (wd719x_chip_init(wd) == 0)
+	if (wd719x_chip_init(wd, 0) == 0)
 		result = SUCCESS;
 	else
 		result = FAILED;
@@ -834,7 +835,7 @@ static int wd719x_board_found(struct Scsi_Host *sh)
 	/* read parameters from EEPROM */
 	wd719x_read_eeprom(wd);
 
-	ret = wd719x_chip_init(wd);
+	ret = wd719x_chip_init(wd, 1);
 	if (ret)
 		goto fail_free_irq;
 
-- 
2.19.1