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Subject[PATCH AUTOSEL 3.18 86/98] Revert "SCSI: Fix NULL pointer dereference in runtime PM"
Date
From: Ken Xue <ken.xue@amd.com>

[ Upstream commit 1c69d3b6eb73e466ecbb8edaf1bc7fd585b288da ]

This reverts commit 49718f0fb8c9 ("SCSI: Fix NULL pointer dereference in
runtime PM")

The old commit may lead to a issue that blk_{pre|post}_runtime_suspend and
blk_{pre|post}_runtime_resume may not be called in pairs.

Take sr device as example, when sr device goes to runtime suspend,
blk_{pre|post}_runtime_suspend will be called since sr device defined
pm->runtime_suspend. But blk_{pre|post}_runtime_resume will not be called
since sr device doesn't have pm->runtime_resume. so, sr device can not
resume correctly anymore.

More discussion can be found from below link.
http://marc.info/?l=linux-scsi&m=144163730531875&w=2

Signed-off-by: Ken Xue <Ken.Xue@amd.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Xiangliang Yu <Xiangliang.Yu@amd.com>
Cc: James E.J. Bottomley <JBottomley@odin.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Michael Terry <Michael.terry@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/scsi_pm.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
index a2dcf6a54ec6..75320dad9677 100644
--- a/drivers/scsi/scsi_pm.c
+++ b/drivers/scsi/scsi_pm.c
@@ -221,13 +221,13 @@ static int sdev_runtime_suspend(struct device *dev)
struct scsi_device *sdev = to_scsi_device(dev);
int err = 0;

- if (pm && pm->runtime_suspend) {
- err = blk_pre_runtime_suspend(sdev->request_queue);
- if (err)
- return err;
+ err = blk_pre_runtime_suspend(sdev->request_queue);
+ if (err)
+ return err;
+ if (pm && pm->runtime_suspend)
err = pm->runtime_suspend(dev);
- blk_post_runtime_suspend(sdev->request_queue, err);
- }
+ blk_post_runtime_suspend(sdev->request_queue, err);
+
return err;
}

@@ -250,11 +250,11 @@ static int sdev_runtime_resume(struct device *dev)
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
int err = 0;

- if (pm && pm->runtime_resume) {
- blk_pre_runtime_resume(sdev->request_queue);
+ blk_pre_runtime_resume(sdev->request_queue);
+ if (pm && pm->runtime_resume)
err = pm->runtime_resume(dev);
- blk_post_runtime_resume(sdev->request_queue, err);
- }
+ blk_post_runtime_resume(sdev->request_queue, err);
+
return err;
}

--
2.17.1
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