@detached is set under the protection of sg_index_lock. Without getting the
lock, new sfp will be added during sg removal and there is no chance for it
to be picked out. So check with sg_index_lock held in sg_add_sfp().
Signed-off-by: Vaughan Cao <vaughan....@oracle.com>
---
drivers/scsi/sg.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 671b760..4d2a19f 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -196,7 +196,7 @@ static void sg_remove_scat(Sg_scatter_hold * schp);
static void sg_build_reserve(Sg_fd * sfp, int req_size);
static void sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size);
static void sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp);
-static Sg_fd *sg_add_sfp(Sg_device * sdp, int dev);
+static Sg_fd *sg_add_sfp(Sg_device * sdp, int dev, int * reason);
static void sg_remove_sfp(struct kref *);
static Sg_request *sg_get_rq_mark(Sg_fd * sfp, int pack_id);
static Sg_request *sg_add_request(Sg_fd * sfp);
@@ -295,21 +295,14 @@ sg_open(struct inode *inode, struct file *filp)
if (flags & O_EXCL)
sdp->exclude = 1; /* used by release lock */
- if (sdp->detached) {
- retval = -ENODEV;
- goto sem_out;
- }
if (sfds_list_empty(sdp)) { /* no existing opens on this device */
sdp->sgdebug = 0;
q = sdp->device->request_queue;
sdp->sg_tablesize = queue_max_segments(q);
}
- if ((sfp = sg_add_sfp(sdp, dev)))
- filp->private_data = sfp;
- else {
- retval = -ENOMEM;
+ if (!(sfp = sg_add_sfp(sdp, dev, &retval)))
goto sem_out;
- }
+ filp->private_data = sfp;
retval = 0;
if (retval) {
@@ -2047,15 +2040,18 @@ sg_remove_request(Sg_fd * sfp, Sg_request * srp)
}
static Sg_fd *
-sg_add_sfp(Sg_device * sdp, int dev)
+sg_add_sfp(Sg_device * sdp, int dev, int * reason)
{
Sg_fd *sfp;
unsigned long iflags;
int bufflen;
sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN);
- if (!sfp)
+ if (!sfp) {
+ if (reason)
+ *reason = -ENOMEM;
return NULL;
+ }
init_waitqueue_head(&sfp->read_wait);
rwlock_init(&sfp->rq_list_lock);
@@ -2070,6 +2066,12 @@ sg_add_sfp(Sg_device * sdp, int dev)
sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
sfp->parentdp = sdp;
write_lock_irqsave(&sg_index_lock, iflags);
+ if (sdp->detached) {
+ write_unlock_irqrestore(&sg_index_lock, iflags);
+ if (reason)
+ *reason = -ENODEV;
+ return NULL;
+ }
list_add_tail(&sfp->sfd_siblings, &sdp->sfds);
write_unlock_irqrestore(&sg_index_lock, iflags);
SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp));
--
1.7.11.7
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