[PATCH] memstick: core: Remove the host ID after device_del()

[PATCH] memstick: core: Remove the host ID after device_del()

[Changyul Lee]

memstick_remove_host() removes the host ID from memstick_host_idr
before device_del() removes the "memstick<N>" device. A host added in
between, for example by another card reader being probed, can get the
same ID, and its device_add() fails:

  sysfs: cannot create duplicate filename '/class/memstick_host/memstick0'

Remove the ID after device_del(), as the error path of
memstick_add_host() already does.

Fixes: baf8532a147d ("memstick: initial commit for Sony MemoryStick support")
Signed-off-by: Changyul Lee <lcy8047@gmail.com>
---
Found with a static analysis tool we are developing.

Reproduced in QEMU (x86_64) with a test module that runs two kthreads
for 20 seconds. Each kthread allocates, adds, removes and frees a host
in a loop, under its own platform device as the parent. Without this
patch, device_add() failed with the error above 3713 to 4442 times per
run in three runs. With it, it never failed in three runs.
Not tested on MemoryStick hardware.

 drivers/memstick/core/memstick.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c
index 0d15f48ef51d..98057ffa1bf7 100644
--- a/drivers/memstick/core/memstick.c
+++ b/drivers/memstick/core/memstick.c
@@ -562,10 +562,10 @@ void memstick_remove_host(struct memstick_host *host)
 	host->set_param(host, MEMSTICK_POWER, MEMSTICK_POWER_OFF);
 	mutex_unlock(&host->lock);
 
+	device_del(&host->dev);
 	spin_lock(&memstick_host_lock);
 	idr_remove(&memstick_host_idr, host->id);
 	spin_unlock(&memstick_host_lock);
-	device_del(&host->dev);
 }
 EXPORT_SYMBOL(memstick_remove_host);
 

base-commit: 7475ea8b58616b33c04afb976cf0fbaad9dd63fb
-- 
2.43.0