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author | Bart Van Assche <bvanassche@acm.org> | 2019-04-30 14:39:18 -0700 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2019-06-18 19:46:17 -0400 |
commit | f049cf1a7b6737c75884247c3f6383ef104d255a (patch) | |
tree | 61d07831c939b6c41fa4c4a5ca27e63df7047679 /drivers/scsi/sd.c | |
parent | 50a1ea5bebbc663be0b794ece96d47aa8d959528 (diff) | |
download | linux-f049cf1a7b6737c75884247c3f6383ef104d255a.tar.gz linux-f049cf1a7b6737c75884247c3f6383ef104d255a.tar.bz2 linux-f049cf1a7b6737c75884247c3f6383ef104d255a.zip |
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.c | 12 |
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); |