Add exclusive trace access

Signed-off-by: Alexey Skidanov <Alexey.Skidanov@amd.com>

src/openclose.c

@@ -33,6 +33,8 @@
 #include "fmm.h"
 
 static const char kfd_device_name[] = "/dev/kfd";
+static const char tmp_file[] = "/var/lock/.amd_hsa_thunk_lock";
+int amd_hsa_thunk_lock_fd = 0;
 
 HSAKMT_STATUS
 HSAKMTAPI
@@ -59,6 +61,11 @@ hsaKmtOpenKFD(void)
 		{
 			result = HSAKMT_STATUS_KERNEL_IO_CHANNEL_NOT_OPENED;
 		}
+
+		amd_hsa_thunk_lock_fd = open(tmp_file,
+				O_CREAT | //create the file if it's not present.
+				O_RDWR, //only need write access for the internal locking semantics.
+				S_IRUSR | S_IWUSR); //permissions on the file, 600 here.
 	}
 	else
 	{
@@ -84,6 +91,12 @@ hsaKmtCloseKFD(void)
 		if (--kfd_open_count == 0)
 		{
 			close(kfd_fd);
+
+			if (amd_hsa_thunk_lock_fd > 0) {
+				close(amd_hsa_thunk_lock_fd);
+				unlink(tmp_file);
+			}
+
 		}
 
 		result = HSAKMT_STATUS_SUCCESS;

src/perfctr.c

@@ -27,6 +27,7 @@
 #include "libhsakmt.h"
 #include "pmc_table.h"
 #include "linux/kfd_ioctl.h"
+#include <unistd.h>
 
 #define BITS_PER_BYTE                   CHAR_BIT
 
@@ -43,6 +44,8 @@ struct perf_trace {
     enum perf_trace_state state;
 };
 
+extern int amd_hsa_thunk_lock_fd;
+
 static HsaCounterProperties *counter_props[MAX_NODES] = {NULL};
 
 static int blockid2uuid(enum perf_block_id block_id, HSA_UUID *uuid)
@@ -248,7 +251,15 @@ hsaKmtPmcAcquireTraceAccess(
     if (trace->magic4cc != HSA_PERF_MAGIC4CC)
         return HSAKMT_STATUS_INVALID_HANDLE;
 
-    return HSAKMT_STATUS_SUCCESS;
+    if (amd_hsa_thunk_lock_fd > 0) {
+	if (lockf( amd_hsa_thunk_lock_fd, F_TLOCK, 0 ) != 0)
+	    return HSAKMT_STATUS_ERROR;
+	else
+	   return HSAKMT_STATUS_SUCCESS;
+    }
+    else {
+	    return HSAKMT_STATUS_ERROR;
+    }
 }
 
 
@@ -274,7 +285,16 @@ hsaKmtPmcReleaseTraceAccess(
     if (trace->magic4cc != HSA_PERF_MAGIC4CC)
         return HSAKMT_STATUS_INVALID_HANDLE;
 
-    return HSAKMT_STATUS_SUCCESS;
+    if (amd_hsa_thunk_lock_fd > 0) {
+	if (lockf( amd_hsa_thunk_lock_fd, F_ULOCK, 0 ) != 0)
+	    return HSAKMT_STATUS_ERROR;
+	else
+	   return HSAKMT_STATUS_SUCCESS;
+    }
+    else {
+	    return HSAKMT_STATUS_ERROR;
+    }
+
 }