SCSI fixes on 20131028
This is a set of four patches that revert functionality introduced in the
merge window to sg. The locking changes turned out to introduce this bug:
[ 205.372901] [ BUG: lock held when returning to user space! ]
[...]
[ 205.373285] #0: (&sdp->o_sem){.+.+..}, at: [<ffffffff8161e650>] sg_open+0x3a0/0x4d0
The fix is large, so at this late stage we'd like to revert the functionality
and start again in the next merge window.
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Pull SCSI fixes from James Bottomley:
"This is a set of four patches that revert functionality introduced in
the merge window to sg. The locking changes turned out to introduce
this bug:
[ 205.372901] [ BUG: lock held when returning to user space! ]
[...]
[ 205.373285] #0: (&sdp->o_sem){.+.+..}, at: [<ffffffff8161e650>] sg_open+0x3a0/0x4d0
The fix is large, so at this late stage we'd like to revert the
functionality and start again in the next merge window"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
[SCSI] Revert "sg: use rwsem to solve race during exclusive open"
[SCSI] Revert "sg: no need sg_open_exclusive_lock"
[SCSI] Revert "sg: checking sdp->detached isn't protected when open"
[SCSI] Revert "sg: push file descriptor list locking down to per-device locking"
hifive-unleashed-5.1
Linus Torvalds
commit
5d914a959d
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@ -105,8 +105,11 @@ static int scatter_elem_sz_prev = SG_SCATTER_SZ;
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static int sg_add(struct device *, struct class_interface *);
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static void sg_remove(struct device *, struct class_interface *);
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static DEFINE_SPINLOCK(sg_open_exclusive_lock);
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static DEFINE_IDR(sg_index_idr);
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static DEFINE_RWLOCK(sg_index_lock);
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static DEFINE_RWLOCK(sg_index_lock); /* Also used to lock
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file descriptor list for device */
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static struct class_interface sg_interface = {
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.add_dev = sg_add,
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@ -143,7 +146,8 @@ typedef struct sg_request { /* SG_MAX_QUEUE requests outstanding per file */
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} Sg_request;
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typedef struct sg_fd { /* holds the state of a file descriptor */
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struct list_head sfd_siblings; /* protected by sfd_lock of device */
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/* sfd_siblings is protected by sg_index_lock */
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struct list_head sfd_siblings;
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struct sg_device *parentdp; /* owning device */
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wait_queue_head_t read_wait; /* queue read until command done */
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rwlock_t rq_list_lock; /* protect access to list in req_arr */
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@ -166,12 +170,13 @@ typedef struct sg_fd { /* holds the state of a file descriptor */
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typedef struct sg_device { /* holds the state of each scsi generic device */
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struct scsi_device *device;
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wait_queue_head_t o_excl_wait; /* queue open() when O_EXCL in use */
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int sg_tablesize; /* adapter's max scatter-gather table size */
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u32 index; /* device index number */
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spinlock_t sfd_lock; /* protect file descriptor list for device */
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/* sfds is protected by sg_index_lock */
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struct list_head sfds;
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struct rw_semaphore o_sem; /* exclude open should hold this rwsem */
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volatile char detached; /* 0->attached, 1->detached pending removal */
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/* exclude protected by sg_open_exclusive_lock */
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char exclude; /* opened for exclusive access */
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char sgdebug; /* 0->off, 1->sense, 9->dump dev, 10-> all devs */
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struct gendisk *disk;
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@ -220,14 +225,35 @@ static int sg_allow_access(struct file *filp, unsigned char *cmd)
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return blk_verify_command(cmd, filp->f_mode & FMODE_WRITE);
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}
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static int get_exclude(Sg_device *sdp)
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{
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unsigned long flags;
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int ret;
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spin_lock_irqsave(&sg_open_exclusive_lock, flags);
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ret = sdp->exclude;
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spin_unlock_irqrestore(&sg_open_exclusive_lock, flags);
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return ret;
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}
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static int set_exclude(Sg_device *sdp, char val)
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{
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unsigned long flags;
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spin_lock_irqsave(&sg_open_exclusive_lock, flags);
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sdp->exclude = val;
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spin_unlock_irqrestore(&sg_open_exclusive_lock, flags);
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return val;
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}
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static int sfds_list_empty(Sg_device *sdp)
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{
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unsigned long flags;
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int ret;
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spin_lock_irqsave(&sdp->sfd_lock, flags);
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read_lock_irqsave(&sg_index_lock, flags);
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ret = list_empty(&sdp->sfds);
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spin_unlock_irqrestore(&sdp->sfd_lock, flags);
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read_unlock_irqrestore(&sg_index_lock, flags);
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return ret;
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}
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@ -239,6 +265,7 @@ sg_open(struct inode *inode, struct file *filp)
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struct request_queue *q;
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Sg_device *sdp;
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Sg_fd *sfp;
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int res;
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int retval;
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nonseekable_open(inode, filp);
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@ -267,52 +294,54 @@ sg_open(struct inode *inode, struct file *filp)
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goto error_out;
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}
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if ((flags & O_EXCL) && (O_RDONLY == (flags & O_ACCMODE))) {
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retval = -EPERM; /* Can't lock it with read only access */
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if (flags & O_EXCL) {
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if (O_RDONLY == (flags & O_ACCMODE)) {
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retval = -EPERM; /* Can't lock it with read only access */
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goto error_out;
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}
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if (!sfds_list_empty(sdp) && (flags & O_NONBLOCK)) {
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retval = -EBUSY;
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goto error_out;
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}
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res = wait_event_interruptible(sdp->o_excl_wait,
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((!sfds_list_empty(sdp) || get_exclude(sdp)) ? 0 : set_exclude(sdp, 1)));
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if (res) {
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retval = res; /* -ERESTARTSYS because signal hit process */
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goto error_out;
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}
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} else if (get_exclude(sdp)) { /* some other fd has an exclusive lock on dev */
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if (flags & O_NONBLOCK) {
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retval = -EBUSY;
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goto error_out;
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}
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res = wait_event_interruptible(sdp->o_excl_wait, !get_exclude(sdp));
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if (res) {
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retval = res; /* -ERESTARTSYS because signal hit process */
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goto error_out;
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}
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}
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if (sdp->detached) {
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retval = -ENODEV;
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goto error_out;
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}
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if (flags & O_NONBLOCK) {
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if (flags & O_EXCL) {
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if (!down_write_trylock(&sdp->o_sem)) {
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retval = -EBUSY;
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goto error_out;
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}
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} else {
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if (!down_read_trylock(&sdp->o_sem)) {
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retval = -EBUSY;
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goto error_out;
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}
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}
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} else {
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if (flags & O_EXCL)
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down_write(&sdp->o_sem);
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else
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down_read(&sdp->o_sem);
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}
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/* Since write lock is held, no need to check sfd_list */
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if (flags & O_EXCL)
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sdp->exclude = 1; /* used by release lock */
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if (sfds_list_empty(sdp)) { /* no existing opens on this device */
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sdp->sgdebug = 0;
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q = sdp->device->request_queue;
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sdp->sg_tablesize = queue_max_segments(q);
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}
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sfp = sg_add_sfp(sdp, dev);
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if (!IS_ERR(sfp))
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if ((sfp = sg_add_sfp(sdp, dev)))
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filp->private_data = sfp;
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/* retval is already provably zero at this point because of the
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* check after retval = scsi_autopm_get_device(sdp->device))
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*/
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else {
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retval = PTR_ERR(sfp);
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if (flags & O_EXCL) {
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sdp->exclude = 0; /* undo if error */
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up_write(&sdp->o_sem);
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} else
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up_read(&sdp->o_sem);
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set_exclude(sdp, 0); /* undo if error */
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wake_up_interruptible(&sdp->o_excl_wait);
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}
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retval = -ENOMEM;
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goto error_out;
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}
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retval = 0;
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error_out:
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if (retval) {
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scsi_autopm_put_device(sdp->device);
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sdp_put:
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scsi_device_put(sdp->device);
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@ -329,18 +358,13 @@ sg_release(struct inode *inode, struct file *filp)
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{
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Sg_device *sdp;
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Sg_fd *sfp;
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int excl;
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if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
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return -ENXIO;
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SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name));
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excl = sdp->exclude;
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sdp->exclude = 0;
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if (excl)
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up_write(&sdp->o_sem);
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else
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up_read(&sdp->o_sem);
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set_exclude(sdp, 0);
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wake_up_interruptible(&sdp->o_excl_wait);
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scsi_autopm_put_device(sdp->device);
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kref_put(&sfp->f_ref, sg_remove_sfp);
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@ -1391,9 +1415,8 @@ static Sg_device *sg_alloc(struct gendisk *disk, struct scsi_device *scsidp)
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disk->first_minor = k;
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sdp->disk = disk;
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sdp->device = scsidp;
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spin_lock_init(&sdp->sfd_lock);
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INIT_LIST_HEAD(&sdp->sfds);
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init_rwsem(&sdp->o_sem);
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init_waitqueue_head(&sdp->o_excl_wait);
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sdp->sg_tablesize = queue_max_segments(q);
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sdp->index = k;
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kref_init(&sdp->d_ref);
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@ -1526,13 +1549,11 @@ static void sg_remove(struct device *cl_dev, struct class_interface *cl_intf)
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/* Need a write lock to set sdp->detached. */
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write_lock_irqsave(&sg_index_lock, iflags);
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spin_lock(&sdp->sfd_lock);
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sdp->detached = 1;
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list_for_each_entry(sfp, &sdp->sfds, sfd_siblings) {
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wake_up_interruptible(&sfp->read_wait);
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kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP);
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}
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spin_unlock(&sdp->sfd_lock);
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write_unlock_irqrestore(&sg_index_lock, iflags);
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sysfs_remove_link(&scsidp->sdev_gendev.kobj, "generic");
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@ -2043,7 +2064,7 @@ sg_add_sfp(Sg_device * sdp, int dev)
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sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN);
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if (!sfp)
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return ERR_PTR(-ENOMEM);
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return NULL;
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init_waitqueue_head(&sfp->read_wait);
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rwlock_init(&sfp->rq_list_lock);
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@ -2057,13 +2078,9 @@ sg_add_sfp(Sg_device * sdp, int dev)
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sfp->cmd_q = SG_DEF_COMMAND_Q;
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sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
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sfp->parentdp = sdp;
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spin_lock_irqsave(&sdp->sfd_lock, iflags);
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if (sdp->detached) {
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spin_unlock_irqrestore(&sdp->sfd_lock, iflags);
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return ERR_PTR(-ENODEV);
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}
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write_lock_irqsave(&sg_index_lock, iflags);
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list_add_tail(&sfp->sfd_siblings, &sdp->sfds);
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spin_unlock_irqrestore(&sdp->sfd_lock, iflags);
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write_unlock_irqrestore(&sg_index_lock, iflags);
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SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp));
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if (unlikely(sg_big_buff != def_reserved_size))
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sg_big_buff = def_reserved_size;
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@ -2113,9 +2130,10 @@ static void sg_remove_sfp(struct kref *kref)
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struct sg_device *sdp = sfp->parentdp;
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unsigned long iflags;
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spin_lock_irqsave(&sdp->sfd_lock, iflags);
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write_lock_irqsave(&sg_index_lock, iflags);
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list_del(&sfp->sfd_siblings);
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spin_unlock_irqrestore(&sdp->sfd_lock, iflags);
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write_unlock_irqrestore(&sg_index_lock, iflags);
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wake_up_interruptible(&sdp->o_excl_wait);
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INIT_WORK(&sfp->ew.work, sg_remove_sfp_usercontext);
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schedule_work(&sfp->ew.work);
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@ -2502,7 +2520,7 @@ static int sg_proc_seq_show_devstrs(struct seq_file *s, void *v)
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return 0;
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}
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/* must be called while holding sg_index_lock and sfd_lock */
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/* must be called while holding sg_index_lock */
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static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp)
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{
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int k, m, new_interface, blen, usg;
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@ -2587,26 +2605,22 @@ static int sg_proc_seq_show_debug(struct seq_file *s, void *v)
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read_lock_irqsave(&sg_index_lock, iflags);
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sdp = it ? sg_lookup_dev(it->index) : NULL;
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if (sdp) {
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spin_lock(&sdp->sfd_lock);
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if (!list_empty(&sdp->sfds)) {
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struct scsi_device *scsidp = sdp->device;
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if (sdp && !list_empty(&sdp->sfds)) {
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struct scsi_device *scsidp = sdp->device;
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seq_printf(s, " >>> device=%s ", sdp->disk->disk_name);
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if (sdp->detached)
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seq_printf(s, "detached pending close ");
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else
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seq_printf
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(s, "scsi%d chan=%d id=%d lun=%d em=%d",
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scsidp->host->host_no,
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scsidp->channel, scsidp->id,
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scsidp->lun,
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scsidp->host->hostt->emulated);
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seq_printf(s, " sg_tablesize=%d excl=%d\n",
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sdp->sg_tablesize, sdp->exclude);
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sg_proc_debug_helper(s, sdp);
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}
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spin_unlock(&sdp->sfd_lock);
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seq_printf(s, " >>> device=%s ", sdp->disk->disk_name);
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if (sdp->detached)
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seq_printf(s, "detached pending close ");
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else
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seq_printf
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(s, "scsi%d chan=%d id=%d lun=%d em=%d",
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scsidp->host->host_no,
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scsidp->channel, scsidp->id,
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scsidp->lun,
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scsidp->host->hostt->emulated);
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seq_printf(s, " sg_tablesize=%d excl=%d\n",
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sdp->sg_tablesize, get_exclude(sdp));
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sg_proc_debug_helper(s, sdp);
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}
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read_unlock_irqrestore(&sg_index_lock, iflags);
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return 0;
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Loading…
Reference in New Issue