3.18-stable review patch. If anyone has any objections, please let me know.
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[ 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; }