[SCSI] sym53c8xx_2: slave_alloc/destroy safety (2.6.27.5)

Make the sym53c8xx_2 driver slave_alloc/destroy less unsafe. References
to the destroyed LCB are cleared from the target structure (instead of
leaving a dangling pointer), and when the last LCB for the target is
destroyed the reference to the upper layer target data is cleared. The
host lock is used to prevent a race with the interrupt handler. Also
user commands are prevented for targets with all LCBs destroyed.

Signed-off-by: Aaro Koskinen <Aaro.Koskinen@nokia.com>
Tested-by: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

3 files changed, 93 insertions, 15 deletions

diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c b/drivers/scsi/sym53c8xx_2/sym_glue.c
index 583966ec8266..45374d66d26a 100644
--- a/drivers/scsi/sym53c8xx_2/sym_glue.c
+++ b/drivers/scsi/sym53c8xx_2/sym_glue.c
@@ -737,11 +737,14 @@ static int sym53c8xx_slave_alloc(struct scsi_device *sdev)
         struct sym_hcb *np = sym_get_hcb(sdev->host);
         struct sym_tcb *tp = &np->target[sdev->id];
         struct sym_lcb *lp;
+        unsigned long flags;
+        int error;
 
         if (sdev->id >= SYM_CONF_MAX_TARGET || sdev->lun >= SYM_CONF_MAX_LUN)
                 return -ENXIO;
 
-        tp->starget = sdev->sdev_target;
+        spin_lock_irqsave(np->s.host->host_lock, flags);
+
         /*
          * Fail the device init if the device is flagged NOSCAN at BOOT in
          * the NVRAM.  This may speed up boot and maintain coherency with
@@ -753,26 +756,37 @@ static int sym53c8xx_slave_alloc(struct scsi_device *sdev)
 
         if (tp->usrflags & SYM_SCAN_BOOT_DISABLED) {
                 tp->usrflags &= ~SYM_SCAN_BOOT_DISABLED;
-                starget_printk(KERN_INFO, tp->starget,
+                starget_printk(KERN_INFO, sdev->sdev_target,
                                 "Scan at boot disabled in NVRAM\n");
-                return -ENXIO;
+                error = -ENXIO;
+                goto out;
         }
 
         if (tp->usrflags & SYM_SCAN_LUNS_DISABLED) {
-                if (sdev->lun != 0)
-                        return -ENXIO;
-                starget_printk(KERN_INFO, tp->starget,
+                if (sdev->lun != 0) {
+                        error = -ENXIO;
+                        goto out;
+                }
+                starget_printk(KERN_INFO, sdev->sdev_target,
                                 "Multiple LUNs disabled in NVRAM\n");
         }
 
         lp = sym_alloc_lcb(np, sdev->id, sdev->lun);
-        if (!lp)
-                return -ENOMEM;
+        if (!lp) {
+                error = -ENOMEM;
+                goto out;
+        }
+        if (tp->nlcb == 1)
+                tp->starget = sdev->sdev_target;
 
         spi_min_period(tp->starget) = tp->usr_period;
         spi_max_width(tp->starget) = tp->usr_width;
 
-        return 0;
+        error = 0;
+out:
+        spin_unlock_irqrestore(np->s.host->host_lock, flags);
+
+        return error;
 }
 
 /*
@@ -819,12 +833,34 @@ static int sym53c8xx_slave_configure(struct scsi_device *sdev)
 static void sym53c8xx_slave_destroy(struct scsi_device *sdev)
 {
         struct sym_hcb *np = sym_get_hcb(sdev->host);
-        struct sym_lcb *lp = sym_lp(&np->target[sdev->id], sdev->lun);
+        struct sym_tcb *tp = &np->target[sdev->id];
+        struct sym_lcb *lp = sym_lp(tp, sdev->lun);
+        unsigned long flags;
+
+        spin_lock_irqsave(np->s.host->host_lock, flags);
+
+        if (lp->busy_itlq || lp->busy_itl) {
+                /*
+                 * This really shouldn't happen, but we can't return an error
+                 * so let's try to stop all on-going I/O.
+                 */
+                starget_printk(KERN_WARNING, tp->starget,
+                               "Removing busy LCB (%d)\n", sdev->lun);
+                sym_reset_scsi_bus(np, 1);
+        }
 
-        if (lp->itlq_tbl)
-                sym_mfree_dma(lp->itlq_tbl, SYM_CONF_MAX_TASK * 4, "ITLQ_TBL");
-        kfree(lp->cb_tags);
-        sym_mfree_dma(lp, sizeof(*lp), "LCB");
+        if (sym_free_lcb(np, sdev->id, sdev->lun) == 0) {
+                /*
+                 * It was the last unit for this target.
+                 */
+                tp->head.sval        = 0;
+                tp->head.wval        = np->rv_scntl3;
+                tp->head.uval        = 0;
+                tp->tgoal.check_nego = 1;
+                tp->starget          = NULL;
+        }
+
+        spin_unlock_irqrestore(np->s.host->host_lock, flags);
 }
 
 /*
@@ -890,6 +926,8 @@ static void sym_exec_user_command (struct sym_hcb *np, struct sym_usrcmd *uc)
                         if (!((uc->target >> t) & 1))
                                 continue;
                         tp = &np->target[t];
+                        if (!tp->nlcb)
+                                continue;
 
                         switch (uc->cmd) {
 
diff --git a/drivers/scsi/sym53c8xx_2/sym_hipd.c b/drivers/scsi/sym53c8xx_2/sym_hipd.c
index 60d6a6d23088..69ad4945c936 100644
--- a/drivers/scsi/sym53c8xx_2/sym_hipd.c
+++ b/drivers/scsi/sym53c8xx_2/sym_hipd.c
@@ -4997,7 +4997,7 @@ struct sym_lcb *sym_alloc_lcb (struct sym_hcb *np, u_char tn, u_char ln)
          */
         if (ln && !tp->lunmp) {
                 tp->lunmp = kcalloc(SYM_CONF_MAX_LUN, sizeof(struct sym_lcb *),
-                                GFP_KERNEL);
+                                GFP_ATOMIC);
                 if (!tp->lunmp)
                         goto fail;
         }
@@ -5017,6 +5017,7 @@ struct sym_lcb *sym_alloc_lcb (struct sym_hcb *np, u_char tn, u_char ln)
                 tp->lun0p = lp;
                 tp->head.lun0_sa = cpu_to_scr(vtobus(lp));
         }
+        tp->nlcb++;
 
         /*
          *  Let the itl task point to error handling.
@@ -5094,6 +5095,43 @@ fail:
 }
 
 /*
+ *  Lun control block deallocation. Returns the number of valid remaing LCBs
+ *  for the target.
+ */
+int sym_free_lcb(struct sym_hcb *np, u_char tn, u_char ln)
+{
+        struct sym_tcb *tp = &np->target[tn];
+        struct sym_lcb *lp = sym_lp(tp, ln);
+
+        tp->nlcb--;
+
+        if (ln) {
+                if (!tp->nlcb) {
+                        kfree(tp->lunmp);
+                        sym_mfree_dma(tp->luntbl, 256, "LUNTBL");
+                        tp->lunmp = NULL;
+                        tp->luntbl = NULL;
+                        tp->head.luntbl_sa = cpu_to_scr(vtobus(np->badluntbl));
+                } else {
+                        tp->luntbl[ln] = cpu_to_scr(vtobus(&np->badlun_sa));
+                        tp->lunmp[ln] = NULL;
+                }
+        } else {
+                tp->lun0p = NULL;
+                tp->head.lun0_sa = cpu_to_scr(vtobus(&np->badlun_sa));
+        }
+
+        if (lp->itlq_tbl) {
+                sym_mfree_dma(lp->itlq_tbl, SYM_CONF_MAX_TASK*4, "ITLQ_TBL");
+                kfree(lp->cb_tags);
+        }
+
+        sym_mfree_dma(lp, sizeof(*lp), "LCB");
+
+        return tp->nlcb;
+}
+
+/*
  *  Queue a SCSI IO to the controller.
  */
 int sym_queue_scsiio(struct sym_hcb *np, struct scsi_cmnd *cmd, struct sym_ccb *cp)
diff --git a/drivers/scsi/sym53c8xx_2/sym_hipd.h b/drivers/scsi/sym53c8xx_2/sym_hipd.h
index 9ebc8706b6bf..053e63c86822 100644
--- a/drivers/scsi/sym53c8xx_2/sym_hipd.h
+++ b/drivers/scsi/sym53c8xx_2/sym_hipd.h
@@ -401,6 +401,7 @@ struct sym_tcb {
          *  An array of bus addresses is used on reselection.
          */
         u32     *luntbl;        /* LCBs bus address table       */
+        int     nlcb;           /* Number of valid LCBs (including LUN #0) */
 
         /*
          *  LUN table used by the C code.
@@ -1065,6 +1066,7 @@ int sym_clear_tasks(struct sym_hcb *np, int cam_status, int target, int lun, int
 struct sym_ccb *sym_get_ccb(struct sym_hcb *np, struct scsi_cmnd *cmd, u_char tag_order);
 void sym_free_ccb(struct sym_hcb *np, struct sym_ccb *cp);
 struct sym_lcb *sym_alloc_lcb(struct sym_hcb *np, u_char tn, u_char ln);
+int sym_free_lcb(struct sym_hcb *np, u_char tn, u_char ln);
 int sym_queue_scsiio(struct sym_hcb *np, struct scsi_cmnd *csio, struct sym_ccb *cp);
 int sym_abort_scsiio(struct sym_hcb *np, struct scsi_cmnd *ccb, int timed_out);
 int sym_reset_scsi_target(struct sym_hcb *np, int target);