[OS-BUILD PATCHv2] scsi: sd: Add "probe_type" module parameter to allow synchronous probing

[Ewan D. Milne (via Email Bridge)]

From: Ewan D. Milne <emilne(a)redhat.com&gt;

scsi: sd: Add "probe_type" module parameter to allow synchronous probing

Setting probe_type="sync" will force synchronous probing in the driver
core, which forces the ordering of minor device number assignments when
SCSI disk devices are probed, for compatibility with prior versions of RHEL.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2140017
Upstream Status: RHEL-only

Signed-off-by: Ewan D. Milne <emilne(a)redhat.com&gt;

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index blahblah..blahblah 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -129,6 +129,14 @@ static const char *sd_cache_types[] = {
 	"write back, no read (daft)"
 };
 
+static const char *sd_probe_types[] = { "async", "sync" };
+
+static char sd_probe_type[6] = "async";
+module_param_string(probe, sd_probe_type, sizeof(sd_probe_type),
+		    S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(probe, "async or sync. Setting to 'sync' disables
asynchronous "
+		 "device number assignments (sda, sdb, ...).");
+
 static void sd_set_flush_flag(struct scsi_disk *sdkp)
 {
 	bool wc = false, fua = false;
@@ -3857,6 +3865,8 @@ static int __init init_sd(void)
 		goto err_out_class;
 	}
 
+	if (!strcmp(sd_probe_type, "sync"))
+		sd_template.gendrv.probe_type = PROBE_FORCE_SYNCHRONOUS;
 	err = scsi_register_driver(&sd_template.gendrv);
 	if (err)
 		goto err_out_driver;

--
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/2504

[Tomas Henzl (via Email Bridge)]

From: Tomas Henzl on gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/2504#note_1451...

I agree with everything you wrote. But the people don't ask for a sync
parameter but for "keep disk order consistent" so as is the associated bz
named, that was behind my idea that we should explicitly say instead of
"disables asynchronous device number assignments (sda, sdb, ...)" with
something where we would mention that there is no ordering guarantee with this
patch.
That is in the end just nitpicking, so feel free to resolve this thread.

[Ewan D. Milne (via Email Bridge)]

From: Ewan D. Milne on gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/2504#note_1465...

OK