From d8256d487840f9c2c372f8fc615a5d378bc133f1 Mon Sep 17 00:00:00 2001
From: Alex Dubov <oakad@yahoo.com>
Date: Wed, 12 Jan 2011 17:01:04 -0800
Subject: [PATCH] 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>
---
drivers/memstick/core/memstick.c | 18 +++++++++++-------
drivers/memstick/core/mspro_block.c | 6 ++++--
2 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c
index 4303b7ef73e28..e9a3eab7b0cf4 100644
--- a/drivers/memstick/core/memstick.c
+++ b/drivers/memstick/core/memstick.c
@@ -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);
diff --git a/drivers/memstick/core/mspro_block.c b/drivers/memstick/core/mspro_block.c
index 02362eccc5886..a167938d4517b 100644
--- a/drivers/memstick/core/mspro_block.c
+++ b/drivers/memstick/core/mspro_block.c
@@ -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))
+ mutex_lock(&mspro_block_disk_lock);
+ if (!idr_pre_get(&mspro_block_disk_idr, GFP_KERNEL)) {
+ mutex_unlock(&mspro_block_disk_lock);
return -ENOMEM;
+ }
- mutex_lock(&mspro_block_disk_lock);
rc = idr_get_new(&mspro_block_disk_idr, card, &disk_id);
mutex_unlock(&mspro_block_disk_lock);
--
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