sg_io_owned needs to be set before the command is sent to the midlevel;
otherwise, a quickly-completing command may cause a different CPU
to see "srp->done == 1 && !srp->sg_io_owned", which would lead to
incorrect behavior.
Check srp->done and set srp->orphan while holding rq_list_lock to
prevent races with sg_rq_end_io().
Signed-off-by: Tony Battersby <tonyb@xxxxxxxxxxxxxxx>
---
sg.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
--- linux-2.6.28/drivers/scsi/sg.c.orig 2009-01-05 11:08:09.000000000 -0500
+++ linux-2.6.28/drivers/scsi/sg.c 2009-01-05 11:10:46.000000000 -0500
@@ -197,7 +197,7 @@ static ssize_t sg_new_read(Sg_fd * sfp,
Sg_request * srp);
static ssize_t sg_new_write(Sg_fd *sfp, struct file *file,
const char __user *buf, size_t count, int blocking,
- int read_only, Sg_request **o_srp);
+ int read_only, int sg_io_owned, Sg_request **o_srp);
static int sg_common_write(Sg_fd * sfp, Sg_request * srp,
unsigned char *cmnd, int timeout, int blocking);
static int sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer);
@@ -607,7 +607,8 @@ sg_write(struct file *filp, const char _
return -EFAULT;
blocking = !(filp->f_flags & O_NONBLOCK);
if (old_hdr.reply_len < 0)
- return sg_new_write(sfp, filp, buf, count, blocking, 0, NULL);
+ return sg_new_write(sfp, filp, buf, count,
+ blocking, 0, 0, NULL);
if (count < (SZ_SG_HEADER + 6))
return -EIO; /* The minimum scsi command length is 6 bytes. */
@@ -688,7 +689,7 @@ sg_write(struct file *filp, const char _
static ssize_t
sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,
- size_t count, int blocking, int read_only,
+ size_t count, int blocking, int read_only, int sg_io_owned,
Sg_request **o_srp)
{
int k;
@@ -708,6 +709,7 @@ sg_new_write(Sg_fd *sfp, struct file *fi
SCSI_LOG_TIMEOUT(1, printk("sg_new_write: queue full\n"));
return -EDOM;
}
+ srp->sg_io_owned = sg_io_owned;
hp = &srp->header;
if (__copy_from_user(hp, buf, SZ_SG_IO_HDR)) {
sg_remove_request(sfp, srp);
@@ -854,10 +856,9 @@ sg_ioctl(struct inode *inode, struct fil
return -EFAULT;
result =
sg_new_write(sfp, filp, p, SZ_SG_IO_HDR,
- blocking, read_only, &srp);
+ blocking, read_only, 1, &srp);
if (result < 0)
return result;
- srp->sg_io_owned = 1;
while (1) {
result = 0; /* following macro to beat race condition */
__wait_event_interruptible(sfp->read_wait,
@@ -867,14 +868,16 @@ sg_ioctl(struct inode *inode, struct fil
return -ENODEV;
if (sfp->closed)
return 0; /* request packet dropped already */
- if (0 == result)
+ write_lock_irq(&sfp->rq_list_lock);
+ if (srp->done) {
+ srp->done = 2;
+ write_unlock_irq(&sfp->rq_list_lock);
break;
+ }
srp->orphan = 1;
+ write_unlock_irq(&sfp->rq_list_lock);
return result; /* -ERESTARTSYS because signal hit process */
}
- write_lock_irqsave(&sfp->rq_list_lock, iflags);
- srp->done = 2;
- write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
result = sg_new_read(sfp, p, SZ_SG_IO_HDR, srp);
return (result < 0) ? result : 0;
}
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