IB/hfi1: Correct unnecessary acquisition of HW mutex

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@intel.com>
Signed-off-by: Grzegorz Morys <grzegorz.morys@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/drivers/infiniband/hw/hfi1/firmware.c b/drivers/infiniband/hw/hfi1/firmware.c
index 001698b744ee08a1003b9eecad5c3d5880234110..cea0d4f3248fa8023f14395c9ee5a04b6d75d96c 100644 (file)
--- a/drivers/infiniband/hw/hfi1/firmware.c
+++ b/drivers/infiniband/hw/hfi1/firmware.c
@@ -1387,7 +1387,14 @@ 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;
@@ -1418,7 +1425,15 @@ 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 */