MTL OFI: Fix race condition due to global progress entries array

Since progress entries array is globally allocated, it is susceptible
to race conditions when using multi-threaded applications. Allocating it
on the stack resolves any potential races as it is thread local by default.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@intel.com>

ompi/mca/mtl/ofi/mtl_ofi.h

@@ -59,6 +59,7 @@ ompi_mtl_ofi_progress(void)
     int count = 0, i, events_read;
     struct fi_cq_err_entry error = { 0 };
     ompi_mtl_ofi_request_t *ofi_req = NULL;
+    struct fi_cq_tagged_entry wc[ompi_mtl_ofi.ofi_progress_event_count];
 
     /**
      * Read the work completions from the CQ.
@@ -66,16 +67,15 @@ ompi_mtl_ofi_progress(void)
      * Call the request's callback.
      */
     while (true) {
-        ret = fi_cq_read(ompi_mtl_ofi.cq, ompi_mtl_ofi.progress_entries,
-                ompi_mtl_ofi.ofi_progress_event_count);
+        ret = fi_cq_read(ompi_mtl_ofi.cq, (void *)&wc, ompi_mtl_ofi.ofi_progress_event_count);
         if (ret > 0) {
             count+= ret;
             events_read = ret;
             for (i = 0; i < events_read; i++) {
-                if (NULL != ompi_mtl_ofi.progress_entries[i].op_context) {
-                    ofi_req = TO_OFI_REQ(ompi_mtl_ofi.progress_entries[i].op_context);
+                if (NULL != wc[i].op_context) {
+                    ofi_req = TO_OFI_REQ(wc[i].op_context);
                     assert(ofi_req);
-                    ret = ofi_req->event_callback(&ompi_mtl_ofi.progress_entries[i], ofi_req);
+                    ret = ofi_req->event_callback(&wc[i], ofi_req);
                     if (OMPI_SUCCESS != ret) {
                         opal_output(0, "%s:%d: Error returned by request event callback: %zd.\n"
                                        "*** The Open MPI OFI MTL is aborting the MPI job (via exit(3)).\n",

ompi/mca/mtl/ofi/mtl_ofi_component.c

@@ -689,21 +689,6 @@ ompi_mtl_ofi_component_init(bool enable_progress_threads,
         goto error;
     }
 
-    /**
-     * Allocate memory for storing the CQ events read in OFI progress.
-     */
-    ompi_mtl_ofi.progress_entries = calloc(ompi_mtl_ofi.ofi_progress_event_count, sizeof(struct fi_cq_tagged_entry));
-    if (NULL == ompi_mtl_ofi.progress_entries) {
-        opal_output_verbose(1, ompi_mtl_base_framework.framework_output,
-                            "%s:%d: alloc of CQ event storage failed: %s\n",
-                            __FILE__, __LINE__, strerror(errno));
-        goto error;
-    }
-
-    /**
-     * The remote fi_addr will be stored in the ofi_endpoint struct.
-     */
-
     av_attr.type = (MTL_OFI_AV_TABLE == av_type) ? FI_AV_TABLE: FI_AV_MAP;
 
     ret = fi_av_open(ompi_mtl_ofi.domain, &av_attr, &ompi_mtl_ofi.av, NULL);
@@ -825,9 +810,6 @@ error:
     if (ompi_mtl_ofi.fabric) {
         (void) fi_close((fid_t)ompi_mtl_ofi.fabric);
     }
-    if (ompi_mtl_ofi.progress_entries) {
-        free(ompi_mtl_ofi.progress_entries);
-    }
 
     return NULL;
 }
@@ -860,8 +842,6 @@ ompi_mtl_ofi_finalize(struct mca_mtl_base_module_t *mtl)
         goto finalize_err;
     }
 
-    free(ompi_mtl_ofi.progress_entries);
-
     return OMPI_SUCCESS;
 
 finalize_err:

ompi/mca/mtl/ofi/mtl_ofi_types.h

@@ -52,9 +52,6 @@ typedef struct mca_mtl_ofi_module_t {
     /** Maximum number of CQ events to read in OFI Progress */
     int ofi_progress_event_count;
 
-    /** CQ event storage */
-    struct fi_cq_tagged_entry *progress_entries;
-
     /** Use FI_REMOTE_CQ_DATA*/
     bool fi_cq_data;