[PATCH 02/12] scsi: Add IRQ_DISABLE_SCSI_QCMD wrapper

["Nicholas A. Bellinger" <nab@linux-iscsi.org>]

From: Nicholas Bellinger <nab@linux-iscsi.org>

This patch adds a IRQ_DISABLE_SCSI_QCMD() wrapper macro used by LLDs
that can now run in host_lock less mode, but still need interrupts disabled
using local_irq_save() before calling their lld_queuecommand() dispatcher.

jgarzik says this method is in fact slower than doing a spin_lock_irqsave() on
internal lib_lld_queuecommand() callers (as is done in libiscsi and libata)
but is still needed by the majority of lock_less LLDs.

Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
---
 include/scsi/scsi_host.h |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index e7e3858..321b114 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -521,6 +521,20 @@ struct scsi_host_template {
 		return rc;						\
 	}
 
+/*
+ * Used for LLDs running in lock-less mode, but that still require having
+ * interrupts disable during their lld_queuecommand() dispatch.
+ */
+#define IRQ_DISABLE_SCSI_QCMD(func_name)				\
+	int func_name(struct Scsi_Host *shost, struct scsi_cmnd *cmd)	\
+	{								\
+		unsigned long irq_flags;				\
+		int rc;							\
+		local_irq_save(irq_flags);				\
+		rc = func_name##_irq_disable(cmd, cmd->scsi_done);	\
+		local_irq_restore(irq_flags);				\
+		return rc;						\
+	}
 
 /*
  * shost state: If you alter this, you also need to alter scsi_sysfs.c
-- 
1.7.3.4