[PATCH v1 3/4] mpi3mr: Check admin reply queue from Watchdog

[Ranjan Kumar <ranjan.kumar@broadcom.com>]

Admin reply processing can be called from multiple
contexts(interrupt raised by the controller, driver drains
admin reply queue upon Task Management returned with success
status by firmware).Driver uses a atomic flag for synchronization
among multiple threads/context for draining the admin replies.
Upon entering the admin processing routine,the thread will set the
atomic flag and starts replies processing and while exiting
the routine, the driver resets the flag. But there is a race condition
when one thread(Thread 1) has processed replies and about to reset the
flag but in meantime few more replies posted on queue and
another thread(Thread 2) is called to process replies but
since the synchronization flag is still set, Thread 2 will return
without processing replies and those new replies will not be flushed.

Watchdog thread will monitor the instances when admin ISR/poll call is
returned due to another thread is processing admin replies. If such an
instance is found, driver will call admin ISR to drain replies(if any).

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
---
 drivers/scsi/mpi3mr/mpi3mr.h    |  3 +++
 drivers/scsi/mpi3mr/mpi3mr_fw.c | 10 +++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/mpi3mr/mpi3mr.h b/drivers/scsi/mpi3mr/mpi3mr.h
index ab36aa2dfdc4..3348797bc73f 100644
--- a/drivers/scsi/mpi3mr/mpi3mr.h
+++ b/drivers/scsi/mpi3mr/mpi3mr.h
@@ -1032,6 +1032,8 @@ struct scmd_priv {
  * @admin_reply_base: Admin reply queue base virtual address
  * @admin_reply_dma: Admin reply queue base dma address
  * @admin_reply_q_in_use: Queue is handled by poll/ISR
+ * @admin_pend_isr: Count of unprocessed admin ISR/poll calls
+ * due to another thread processing replies
  * @ready_timeout: Controller ready timeout
  * @intr_info: Interrupt cookie pointer
  * @intr_info_count: Number of interrupt cookies
@@ -1206,6 +1208,7 @@ struct mpi3mr_ioc {
 	void *admin_reply_base;
 	dma_addr_t admin_reply_dma;
 	atomic_t admin_reply_q_in_use;
+	atomic_t admin_pend_isr;
 
 	u32 ready_timeout;
 
diff --git a/drivers/scsi/mpi3mr/mpi3mr_fw.c b/drivers/scsi/mpi3mr/mpi3mr_fw.c
index f83d5c9f29a2..3fcb1ad3b070 100644
--- a/drivers/scsi/mpi3mr/mpi3mr_fw.c
+++ b/drivers/scsi/mpi3mr/mpi3mr_fw.c
@@ -446,8 +446,10 @@ int mpi3mr_process_admin_reply_q(struct mpi3mr_ioc *mrioc)
 	u16 threshold_comps = 0;
 	struct mpi3_default_reply_descriptor *reply_desc;
 
-	if (!atomic_add_unless(&mrioc->admin_reply_q_in_use, 1, 1))
+	if (!atomic_add_unless(&mrioc->admin_reply_q_in_use, 1, 1)) {
+		atomic_inc(&mrioc->admin_pend_isr);
 		return 0;
+	}
 
 	reply_desc = (struct mpi3_default_reply_descriptor *)mrioc->admin_reply_base +
 	    admin_reply_ci;
@@ -2757,6 +2759,12 @@ static void mpi3mr_watchdog_work(struct work_struct *work)
 		return;
 	}
 
+	if (atomic_read(&mrioc->admin_pend_isr)) {
+		ioc_err(mrioc, "Unprocessed admin ISR instance found\n"
+				"flush admin replies\n");
+		mpi3mr_process_admin_reply_q(mrioc);
+	}
+
 	if (!(mrioc->facts.ioc_capabilities &
 		MPI3_IOCFACTS_CAPABILITY_NON_SUPERVISOR_IOC) &&
 		(mrioc->ts_update_counter++ >= mrioc->ts_update_interval)) {
-- 
2.31.1