lkml.org 
[lkml]   [2018]   [Jun]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCHv2] block: fix bsg_unregister and bsg_open race
Thanks, Christoph. Good catch releasing the mutex on failure path.
V2 patch with your suggestions applied.


From 7a8dc4b10f344d915658549581158f3da2cc1f91 Mon Sep 17 00:00:00 2001
From: Anatoliy Glagolev <glagolig@gmail.com>
Date: Wed, 13 Jun 2018 15:38:51 -0600
Subject: [PATCHv2] Fix race of bsg_open and bsg_unregister
Signed-Off-By: Anatoliy Glagolev <glagolig@gmail.com>

---
block/bsg.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/block/bsg.c b/block/bsg.c
index 132e657..66602c4 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -693,6 +693,8 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
struct bsg_device *bd;
unsigned char buf[32];

+ lockdep_assert_held(&bsg_mutex);
+
if (!blk_get_queue(rq))
return ERR_PTR(-ENXIO);

@@ -707,14 +709,12 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
bsg_set_block(bd, file);

atomic_set(&bd->ref_count, 1);
- mutex_lock(&bsg_mutex);
hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));

strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
bsg_dbg(bd, "bound to <%s>, max queue %d\n",
format_dev_t(buf, inode->i_rdev), bd->max_queue);

- mutex_unlock(&bsg_mutex);
return bd;
}

@@ -722,7 +722,7 @@ static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
{
struct bsg_device *bd;

- mutex_lock(&bsg_mutex);
+ lockdep_assert_held(&bsg_mutex);

hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
if (bd->queue == q) {
@@ -732,7 +732,6 @@ static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
}
bd = NULL;
found:
- mutex_unlock(&bsg_mutex);
return bd;
}

@@ -746,17 +745,18 @@ static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
*/
mutex_lock(&bsg_mutex);
bcd = idr_find(&bsg_minor_idr, iminor(inode));
- mutex_unlock(&bsg_mutex);

- if (!bcd)
- return ERR_PTR(-ENODEV);
+ if (!bcd) {
+ bd = ERR_PTR(-ENODEV);
+ goto out_unlock;
+ }

bd = __bsg_get_device(iminor(inode), bcd->queue);
- if (bd)
- return bd;
-
- bd = bsg_add_device(inode, bcd->queue, file);
+ if (!bd)
+ bd = bsg_add_device(inode, bcd->queue, file);

+out_unlock:
+ mutex_unlock(&bsg_mutex);
return bd;
}

--
1.9.1
\
 
 \ /
  Last update: 2018-06-15 01:47    [W:0.980 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site