[SCSI] hpsa: cap CCISS_PASSTHRU at 20 concurrent commands.
Cap CCISS_BIG_PASSTHRU as well. If an attempt is made
to exceed this, ioctl() will return -1 with errno == EAGAIN.
This is to prevent a userland program from exhausting all of
pci_alloc_consistent memory. I've only seen this problem when
running a special test program designed to provoke it. 20
concurrent commands via the passthru ioctls (not counting SG_IO)
should be more than enough.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index bc85e72..6eabf08 100644
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -114,6 +114,11 @@
struct TransTable_struct *transtable;
unsigned long transMethod;
+ /* cap concurrent passthrus at some reasonable maximum */
+#define HPSA_MAX_CONCURRENT_PASSTHRUS (20)
+ spinlock_t passthru_count_lock; /* protects passthru_count */
+ int passthru_count;
+
/*
* Performant mode completion buffers
*/
