IB/ehca: Serialize MR alloc and MR free hvCalls

Some firmware levels exhibit a race condition between H_ALLOC_RESOURCE(MR)
and H_FREE_RESOURCE(MR).  Work around this problem by locking these hvCalls
against each other.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/infiniband/hw/ehca/hcp_if.c b/drivers/infiniband/hw/ehca/hcp_if.c
index 3d68f6536f9c..c16a21374bb5 100644
--- a/drivers/infiniband/hw/ehca/hcp_if.c
+++ b/drivers/infiniband/hw/ehca/hcp_if.c
@@ -120,15 +120,28 @@ static long ehca_plpar_hcall_norets(unsigned long opcode,
                                     unsigned long arg7)
 {
         long ret;
-        int i, sleep_msecs;
+        int i, sleep_msecs, do_lock;
+        unsigned long flags;
 
         ehca_gen_dbg("opcode=%lx " HCALL7_REGS_FORMAT,
                      opcode, arg1, arg2, arg3, arg4, arg5, arg6, arg7);
 
+        /* lock H_FREE_RESOURCE(MR) against itself and H_ALLOC_RESOURCE(MR) */
+        if ((opcode == H_FREE_RESOURCE) && (arg7 == 5)) {
+                arg7 = 0; /* better not upset firmware */
+                do_lock = 1;
+        }
+
         for (i = 0; i < 5; i++) {
+                if (do_lock)
+                        spin_lock_irqsave(&hcall_lock, flags);
+
                 ret = plpar_hcall_norets(opcode, arg1, arg2, arg3, arg4,
                                          arg5, arg6, arg7);
 
+                if (do_lock)
+                        spin_unlock_irqrestore(&hcall_lock, flags);
+
                 if (H_IS_LONG_BUSY(ret)) {
                         sleep_msecs = get_longbusy_msecs(ret);
                         msleep_interruptible(sleep_msecs);
@@ -161,23 +174,24 @@ static long ehca_plpar_hcall9(unsigned long opcode,
                               unsigned long arg9)
 {
         long ret;
-        int i, sleep_msecs, lock_is_set = 0;
+        int i, sleep_msecs, do_lock;
         unsigned long flags = 0;
 
         ehca_gen_dbg("INPUT -- opcode=%lx " HCALL9_REGS_FORMAT, opcode,
                      arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9);
 
+        /* lock H_ALLOC_RESOURCE(MR) against itself and H_FREE_RESOURCE(MR) */
+        do_lock = ((opcode == H_ALLOC_RESOURCE) && (arg2 == 5));
+
         for (i = 0; i < 5; i++) {
-                if ((opcode == H_ALLOC_RESOURCE) && (arg2 == 5)) {
+                if (do_lock)
                         spin_lock_irqsave(&hcall_lock, flags);
-                        lock_is_set = 1;
-                }
 
                 ret = plpar_hcall9(opcode, outs,
                                    arg1, arg2, arg3, arg4, arg5,
                                    arg6, arg7, arg8, arg9);
 
-                if (lock_is_set)
+                if (do_lock)
                         spin_unlock_irqrestore(&hcall_lock, flags);
 
                 if (H_IS_LONG_BUSY(ret)) {
@@ -807,7 +821,7 @@ u64 hipz_h_free_resource_mr(const struct ipz_adapter_handle adapter_handle,
         return ehca_plpar_hcall_norets(H_FREE_RESOURCE,
                                        adapter_handle.handle,    /* r4 */
                                        mr->ipz_mr_handle.handle, /* r5 */
-                                       0, 0, 0, 0, 0);
+                                       0, 0, 0, 0, 5);
 }
 
 u64 hipz_h_reregister_pmr(const struct ipz_adapter_handle adapter_handle,