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Re: [PATCH v2 03/10] nvme-multipath: add error handling support for add_disk()

On 9/28/21 12:00 AM, Luis Chamberlain wrote:
We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling.

Since we now can tell for sure when a disk was added, move
setting the bit NVME_NSHEAD_DISK_LIVE only when we did
add the disk successfully.

Nothing to do here as the cleanup is done elsewhere. We take
care and use test_and_set_bit() because it is protects against
two nvme paths simultaneously calling device_add_disk() on the
same namespace head.

Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
  drivers/nvme/host/multipath.c | 13 +++++++++++--
  1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index e8ccdd398f78..35cace4f3f5f 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -496,13 +496,22 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct 
nvme_ns_head *head)
  static void nvme_mpath_set_live(struct nvme_ns *ns)
        struct nvme_ns_head *head = ns->head;
+       int rc;
if (!head->disk)
+ /*
+        * test_and_set_bit() is used because it is protecting against two nvme
+        * paths simultaneously calling device_add_disk() on the same namespace
+        * head.
+        */
        if (!test_and_set_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) {
-               device_add_disk(&head->subsys->dev, head->disk,
-                               nvme_ns_id_attr_groups);
+               rc = device_add_disk(&head->subsys->dev, head->disk,
+                                    nvme_ns_id_attr_groups);
+               if (rc)
+                       return;
+               set_bit(NVME_NSHEAD_DISK_LIVE, &head->flags);
Setting the same bit twice?
And shouldn't you unset the bit if 'device_add_disk()' fails?


Dr. Hannes Reinecke                Kernel Storage Architect
hare@xxxxxxx                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer



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