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>
diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c
index 4303b7e..e9a3eab 100644
--- a/drivers/memstick/core/memstick.c
+++ b/drivers/memstick/core/memstick.c
@@ -511,14 +511,18 @@
{
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);
diff --git a/drivers/memstick/core/mspro_block.c b/drivers/memstick/core/mspro_block.c
index 02362ec..a167938 100644
--- a/drivers/memstick/core/mspro_block.c
+++ b/drivers/memstick/core/mspro_block.c
@@ -1206,10 +1206,12 @@
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);