[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>

1 files changed, 39 insertions, 1 deletions

diff --git a/drivers/scsi/sym53c8xx_2/sym_hipd.c b/drivers/scsi/sym53c8xx_2/sym_hipd.c
index 60d6a6d2308..69ad4945c93 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)