[PATCH for-next 3/7] IB/hfi1: Correct unnecessary acquisition of HW mutex

[Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

From: Grzegorz Morys <grzegorz.morys-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

Avoid acquiring already acquired hardware mutex and releasing
the unacquired one as these are redundant operations.
Add printouts for such situations to help detect potential errors
within the driver.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Grzegorz Morys <grzegorz.morys-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/infiniband/hw/hfi1/firmware.c |   19 +++++++++++++++++--
 1 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/firmware.c b/drivers/infiniband/hw/hfi1/firmware.c
index b10781d..148a2c7 100644
--- a/drivers/infiniband/hw/hfi1/firmware.c
+++ b/drivers/infiniband/hw/hfi1/firmware.c
@@ -1424,7 +1424,14 @@ int acquire_hw_mutex(struct hfi1_devdata *dd)
 	unsigned long timeout;
 	int try = 0;
 	u8 mask = 1 << dd->hfi1_id;
-	u8 user;
+	u8 user = (u8)read_csr(dd, ASIC_CFG_MUTEX);
+
+	if (user == mask) {
+		dd_dev_info(dd,
+			    "Hardware mutex already acquired, mutex mask %u\n",
+			    (u32)mask);
+		return 0;
+	}
 
 retry:
 	timeout = msecs_to_jiffies(HM_TIMEOUT) + jiffies;
@@ -1455,7 +1462,15 @@ int acquire_hw_mutex(struct hfi1_devdata *dd)
 
 void release_hw_mutex(struct hfi1_devdata *dd)
 {
-	write_csr(dd, ASIC_CFG_MUTEX, 0);
+	u8 mask = 1 << dd->hfi1_id;
+	u8 user = (u8)read_csr(dd, ASIC_CFG_MUTEX);
+
+	if (user != mask)
+		dd_dev_warn(dd,
+			    "Unable to release hardware mutex, mutex mask %u, my mask %u\n",
+			    (u32)user, (u32)mask);
+	else
+		write_csr(dd, ASIC_CFG_MUTEX, 0);
 }
 
 /* return the given resource bit(s) as a mask for the given HFI */

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