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memstick: avert possible race condition between idr_pre_get and idr_get_new 

Implement the usual pattern around idr_pre_get() and idr_get_new() to
handlethe situation where another thread concurrently steals this thread's
idr_pre_get() preallocation.

Signed-off-by: Alex Dubov <oakad@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alex Dubov 2011-01-12 17:01:04 -08:00 committed by Linus Torvalds
parent 8930c8aa74
commit d8256d4878
2 changed files with 16 additions and 10 deletions
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18
drivers/memstick/core/memstick.c
View File

@ -511,14 +511,18 @@ int memstick_add_host(struct memstick_host *host)
{
int rc;
if (!idr_pre_get(&memstick_host_idr, GFP_KERNEL))
return -ENOMEM;
while (1) {
if (!idr_pre_get(&memstick_host_idr, GFP_KERNEL))
return -ENOMEM;
spin_lock(&memstick_host_lock);
rc = idr_get_new(&memstick_host_idr, host, &host->id);
spin_unlock(&memstick_host_lock);
if (rc)
return rc;
spin_lock(&memstick_host_lock);
rc = idr_get_new(&memstick_host_idr, host, &host->id);
spin_unlock(&memstick_host_lock);
if (!rc)
break;
else if (rc != -EAGAIN)
return rc;
}
dev_set_name(&host->dev, "memstick%u", host->id);

8
drivers/memstick/core/mspro_block.c
View File

@ -1206,10 +1206,12 @@ static int mspro_block_init_disk(struct memstick_dev *card)
msb->page_size = be16_to_cpu(sys_info->unit_size);
if (!idr_pre_get(&mspro_block_disk_idr, GFP_KERNEL))
return -ENOMEM;
mutex_lock(&mspro_block_disk_lock);
if (!idr_pre_get(&mspro_block_disk_idr, GFP_KERNEL)) {
mutex_unlock(&mspro_block_disk_lock);
return -ENOMEM;
}
rc = idr_get_new(&mspro_block_disk_idr, card, &disk_id);
mutex_unlock(&mspro_block_disk_lock);