1 files changed, 121 insertions, 29 deletions

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 0a7839db5752..9aadf2fcad6a 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -17,7 +17,7 @@
    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
  */
 
-static char *verstr = "20050501";
+static char *verstr = "20050802";
 
 #include <linux/module.h>
 
@@ -219,6 +219,12 @@ static int switch_partition(struct scsi_tape *);
 
 static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
 
+static void scsi_tape_release(struct kref *);
+
+#define to_scsi_tape(obj) container_of(obj, struct scsi_tape, kref)
+
+static DECLARE_MUTEX(st_ref_sem);
+
 
 #include "osst_detect.h"
 #ifndef SIGS_FROM_OSST
@@ -230,6 +236,46 @@ static int st_int_ioctl(struct scsi_tape *, unsigned int, unsigned long);
         {"OnStream", "FW-", "", "osst"}
 #endif
 
+static struct scsi_tape *scsi_tape_get(int dev)
+{
+        struct scsi_tape *STp = NULL;
+
+        down(&st_ref_sem);
+        write_lock(&st_dev_arr_lock);
+
+        if (dev < st_dev_max && scsi_tapes != NULL)
+                STp = scsi_tapes[dev];
+        if (!STp) goto out;
+
+        kref_get(&STp->kref);
+
+        if (!STp->device)
+                goto out_put;
+
+        if (scsi_device_get(STp->device))
+                goto out_put;
+
+        goto out;
+
+out_put:
+        kref_put(&STp->kref, scsi_tape_release);
+        STp = NULL;
+out:
+        write_unlock(&st_dev_arr_lock);
+        up(&st_ref_sem);
+        return STp;
+}
+
+static void scsi_tape_put(struct scsi_tape *STp)
+{
+        struct scsi_device *sdev = STp->device;
+
+        down(&st_ref_sem);
+        kref_put(&STp->kref, scsi_tape_release);
+        scsi_device_put(sdev);
+        up(&st_ref_sem);
+}
+
 struct st_reject_data {
         char *vendor;
         char *model;
@@ -311,7 +357,7 @@ static int st_chk_result(struct scsi_tape *STp, struct scsi_request * SRpnt)
                 return 0;
 
         cmdstatp = &STp->buffer->cmdstat;
-        st_analyze_sense(STp->buffer->last_SRpnt, cmdstatp);
+        st_analyze_sense(SRpnt, cmdstatp);
 
         if (cmdstatp->have_sense)
                 scode = STp->buffer->cmdstat.sense_hdr.sense_key;
@@ -399,10 +445,10 @@ static void st_sleep_done(struct scsi_cmnd * SCpnt)
 
         (STp->buffer)->cmdstat.midlevel_result = SCpnt->result;
         SCpnt->request->rq_status = RQ_SCSI_DONE;
-        (STp->buffer)->last_SRpnt = SCpnt->sc_request;
         DEB( STp->write_pending = 0; )
 
-        complete(SCpnt->request->waiting);
+        if (SCpnt->request->waiting)
+                complete(SCpnt->request->waiting);
 }
 
 /* Do the scsi command. Waits until command performed if do_wait is true.
@@ -412,8 +458,20 @@ static struct scsi_request *
 st_do_scsi(struct scsi_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd,
            int bytes, int direction, int timeout, int retries, int do_wait)
 {
+        struct completion *waiting;
         unsigned char *bp;
 
+        /* if async, make sure there's no command outstanding */
+        if (!do_wait && ((STp->buffer)->last_SRpnt)) {
+                printk(KERN_ERR "%s: Async command already active.\n",
+                       tape_name(STp));
+                if (signal_pending(current))
+                        (STp->buffer)->syscall_result = (-EINTR);
+                else
+                        (STp->buffer)->syscall_result = (-EBUSY);
+                return NULL;
+        }
+
         if (SRpnt == NULL) {
                 SRpnt = scsi_allocate_request(STp->device, GFP_ATOMIC);
                 if (SRpnt == NULL) {
@@ -427,7 +485,13 @@ st_do_scsi(struct scsi_request * SRpnt, struct scsi_tape * STp, unsigned char *c
                 }
         }
 
-        init_completion(&STp->wait);
+        /* If async IO, set last_SRpnt. This ptr tells write_behind_check
+           which IO is outstanding. It's nulled out when the IO completes. */
+        if (!do_wait)
+                (STp->buffer)->last_SRpnt = SRpnt;
+
+        waiting = &STp->wait;
+        init_completion(waiting);
         SRpnt->sr_use_sg = STp->buffer->do_dio || (bytes > (STp->buffer)->frp[0].length);
         if (SRpnt->sr_use_sg) {
                 if (!STp->buffer->do_dio)
@@ -438,17 +502,20 @@ st_do_scsi(struct scsi_request * SRpnt, struct scsi_tape * STp, unsigned char *c
                 bp = (STp->buffer)->b_data;
         SRpnt->sr_data_direction = direction;
         SRpnt->sr_cmd_len = 0;
-        SRpnt->sr_request->waiting = &(STp->wait);
+        SRpnt->sr_request->waiting = waiting;
         SRpnt->sr_request->rq_status = RQ_SCSI_BUSY;
         SRpnt->sr_request->rq_disk = STp->disk;
+        SRpnt->sr_request->end_io = blk_end_sync_rq;
         STp->buffer->cmdstat.have_sense = 0;
 
         scsi_do_req(SRpnt, (void *) cmd, bp, bytes,
                     st_sleep_done, timeout, retries);
 
         if (do_wait) {
-                wait_for_completion(SRpnt->sr_request->waiting);
+                wait_for_completion(waiting);
                 SRpnt->sr_request->waiting = NULL;
+                if (SRpnt->sr_request->rq_status != RQ_SCSI_DONE)
+                        SRpnt->sr_result |= (DRIVER_ERROR << 24);
                 (STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
         }
         return SRpnt;
@@ -465,6 +532,7 @@ static int write_behind_check(struct scsi_tape * STp)
         struct st_buffer *STbuffer;
         struct st_partstat *STps;
         struct st_cmdstatus *cmdstatp;
+        struct scsi_request *SRpnt;
 
         STbuffer = STp->buffer;
         if (!STbuffer->writing)
@@ -478,10 +546,14 @@ static int write_behind_check(struct scsi_tape * STp)
         ) /* end DEB */
 
         wait_for_completion(&(STp->wait));
-        (STp->buffer)->last_SRpnt->sr_request->waiting = NULL;
+        SRpnt = STbuffer->last_SRpnt;
+        STbuffer->last_SRpnt = NULL;
+        SRpnt->sr_request->waiting = NULL;
+        if (SRpnt->sr_request->rq_status != RQ_SCSI_DONE)
+                SRpnt->sr_result |= (DRIVER_ERROR << 24);
 
-        (STp->buffer)->syscall_result = st_chk_result(STp, (STp->buffer)->last_SRpnt);
-        scsi_release_request((STp->buffer)->last_SRpnt);
+        (STp->buffer)->syscall_result = st_chk_result(STp, SRpnt);
+        scsi_release_request(SRpnt);
 
         STbuffer->buffer_bytes -= STbuffer->writing;
         STps = &(STp->ps[STp->partition]);
@@ -1055,25 +1127,20 @@ static int st_open(struct inode *inode, struct file *filp)
          */
         filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
 
+        if (!(STp = scsi_tape_get(dev)))
+                return -ENXIO;
+
         write_lock(&st_dev_arr_lock);
-        if (dev >= st_dev_max || scsi_tapes == NULL ||
-            ((STp = scsi_tapes[dev]) == NULL)) {
-                write_unlock(&st_dev_arr_lock);
-                return (-ENXIO);
-        }
         filp->private_data = STp;
         name = tape_name(STp);
 
         if (STp->in_use) {
                 write_unlock(&st_dev_arr_lock);
+                scsi_tape_put(STp);
                 DEB( printk(ST_DEB_MSG "%s: Device already in use.\n", name); )
                 return (-EBUSY);
         }
 
-        if(scsi_device_get(STp->device)) {
-                write_unlock(&st_dev_arr_lock);
-                return (-ENXIO);
-        }
         STp->in_use = 1;
         write_unlock(&st_dev_arr_lock);
         STp->rew_at_close = STp->autorew_dev = (iminor(inode) & 0x80) == 0;
@@ -1118,7 +1185,7 @@ static int st_open(struct inode *inode, struct file *filp)
  err_out:
         normalize_buffer(STp->buffer);
         STp->in_use = 0;
-        scsi_device_put(STp->device);
+        scsi_tape_put(STp);
         return retval;
 
 }
@@ -1250,7 +1317,7 @@ static int st_release(struct inode *inode, struct file *filp)
         write_lock(&st_dev_arr_lock);
         STp->in_use = 0;
         write_unlock(&st_dev_arr_lock);
-        scsi_device_put(STp->device);
+        scsi_tape_put(STp);
 
         return result;
 }
@@ -3887,6 +3954,7 @@ static int st_probe(struct device *dev)
                 goto out_put_disk;
         }
         memset(tpnt, 0, sizeof(struct scsi_tape));
+        kref_init(&tpnt->kref);
         tpnt->disk = disk;
         sprintf(disk->disk_name, "st%d", i);
         disk->private_data = &tpnt->driver;
@@ -3902,6 +3970,7 @@ static int st_probe(struct device *dev)
                 tpnt->tape_type = MT_ISSCSI2;
 
         tpnt->buffer = buffer;
+        tpnt->buffer->last_SRpnt = NULL;
 
         tpnt->inited = 0;
         tpnt->dirty = 0;
@@ -4076,15 +4145,10 @@ static int st_remove(struct device *dev)
                                         tpnt->modes[mode].cdevs[j] = NULL;
                                 }
                         }
-                        tpnt->device = NULL;
 
-                        if (tpnt->buffer) {
-                                tpnt->buffer->orig_frp_segs = 0;
-                                normalize_buffer(tpnt->buffer);
-                                kfree(tpnt->buffer);
-                        }
-                        put_disk(tpnt->disk);
-                        kfree(tpnt);
+                        down(&st_ref_sem);
+                        kref_put(&tpnt->kref, scsi_tape_release);
+                        up(&st_ref_sem);
                         return 0;
                 }
         }
@@ -4093,6 +4157,34 @@ static int st_remove(struct device *dev)
         return 0;
 }
 
+/**
+ *      scsi_tape_release - Called to free the Scsi_Tape structure
+ *      @kref: pointer to embedded kref
+ *
+ *      st_ref_sem must be held entering this routine.  Because it is
+ *      called on last put, you should always use the scsi_tape_get()
+ *      scsi_tape_put() helpers which manipulate the semaphore directly
+ *      and never do a direct kref_put().
+ **/
+static void scsi_tape_release(struct kref *kref)
+{
+        struct scsi_tape *tpnt = to_scsi_tape(kref);
+        struct gendisk *disk = tpnt->disk;
+
+        tpnt->device = NULL;
+
+        if (tpnt->buffer) {
+                tpnt->buffer->orig_frp_segs = 0;
+                normalize_buffer(tpnt->buffer);
+                kfree(tpnt->buffer);
+        }
+
+        disk->private_data = NULL;
+        put_disk(disk);
+        kfree(tpnt);
+        return;
+}
+
 static void st_intr(struct scsi_cmnd *SCpnt)
 {
         scsi_io_completion(SCpnt, (SCpnt->result ? 0: SCpnt->bufflen), 1);