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authorBart Van Assche <bvanassche@acm.org>2019-05-01 00:39:18 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2019-06-19 02:46:17 +0300
commitf049cf1a7b6737c75884247c3f6383ef104d255a (patch)
tree61d07831c939b6c41fa4c4a5ca27e63df7047679 /drivers/scsi/sd.c
parent50a1ea5bebbc663be0b794ece96d47aa8d959528 (diff)
downloadlinux-f049cf1a7b6737c75884247c3f6383ef104d255a.tar.xz
scsi: sd: Rely on the driver core for asynchronous probing
As explained during the 2018 LSF/MM session about increasing SCSI disk probing concurrency, the problems with the current probing approach are as follows: - The driver core is unaware of asynchronous SCSI LUN probing. wait_for_device_probe() waits for all asynchronous probes except asynchronous SCSI disk probes. - There is unnecessary serialization between sd_probe() and sd_remove(). This can lead to a deadlock. Hence this patch that modifies the sd driver such that it uses the driver core framework for asynchronous probing. The async domain and get_device()/put_device() pairs that became superfluous due to this change are removed. This patch does not affect the time needed for loading the scsi_debug kernel module with parameters delay=0 and max_luns=256. This patch depends on commit ef0ff68351be ("driver core: Probe devices asynchronously instead of the driver") that went upstream in kernel version v5.1-rc1. Cc: Lee Duncan <lduncan@suse.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Pavel Machek <pavel@ucw.cz> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/sd.c')
-rw-r--r--drivers/scsi/sd.c12
1 files changed, 3 insertions, 9 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index f3564e406160..2ba7eef4105a 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -568,6 +568,7 @@ static struct scsi_driver sd_template = {
.name = "sd",
.owner = THIS_MODULE,
.probe = sd_probe,
+ .probe_type = PROBE_PREFER_ASYNCHRONOUS,
.remove = sd_remove,
.shutdown = sd_shutdown,
.pm = &sd_pm_ops,
@@ -3253,12 +3254,8 @@ static int sd_format_disk_name(char *prefix, int index, char *buf, int buflen)
return 0;
}
-/*
- * The asynchronous part of sd_probe
- */
-static void sd_probe_async(void *data, async_cookie_t cookie)
+static void sd_probe_part2(struct scsi_disk *sdkp)
{
- struct scsi_disk *sdkp = data;
struct scsi_device *sdp;
struct gendisk *gd;
u32 index;
@@ -3313,7 +3310,6 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
sdp->removable ? "removable " : "");
scsi_autopm_put_device(sdp);
- put_device(&sdkp->dev);
}
/**
@@ -3405,8 +3401,7 @@ static int sd_probe(struct device *dev)
get_device(dev);
dev_set_drvdata(dev, sdkp);
- get_device(&sdkp->dev); /* prevent release before async_schedule */
- async_schedule_domain(sd_probe_async, sdkp, &scsi_sd_probe_domain);
+ sd_probe_part2(sdkp);
return 0;
@@ -3442,7 +3437,6 @@ static int sd_remove(struct device *dev)
scsi_autopm_get_device(sdkp->device);
async_synchronize_full_domain(&scsi_sd_pm_domain);
- async_synchronize_full_domain(&scsi_sd_probe_domain);
device_del(&sdkp->dev);
del_gendisk(sdkp->disk);
sd_shutdown(dev);