diff mbox series

[2/3] mem: provide thread-unsafe memseg walk variant

Message ID 311a48e50a626b7a6e8a80b0da79e6c725b79b52.1528796062.git.anatoly.burakov@intel.com (mailing list archive)
State Accepted, archived
Delegated to: Thomas Monjalon
Headers show
Series [1/3] mem: provide thread-unsafe contig walk variant | expand

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK

Commit Message

Anatoly Burakov June 12, 2018, 9:46 a.m. UTC
Sometimes, user code needs to walk memseg list while being inside
a memory-related callback. Rather than making everyone copy around
the same iteration code and depending on DPDK internals, provide an
official way to do memseg_walk() inside callbacks.

Also, remove existing reimplementation from sPAPR VFIO code and use
the new API instead.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/common/eal_common_memory.c  | 28 ++++++++------
 lib/librte_eal/common/include/rte_memory.h | 18 +++++++++
 lib/librte_eal/linuxapp/eal/eal_vfio.c     | 43 +++-------------------
 lib/librte_eal/rte_eal_version.map         |  1 +
 4 files changed, 40 insertions(+), 50 deletions(-)
diff mbox series

Patch

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index e3320a746..afe0d5b57 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -841,14 +841,11 @@  rte_memseg_contig_walk(rte_memseg_contig_walk_t func, void *arg)
 }
 
 int __rte_experimental
-rte_memseg_walk(rte_memseg_walk_t func, void *arg)
+rte_memseg_walk_thread_unsafe(rte_memseg_walk_t func, void *arg)
 {
 	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
 	int i, ms_idx, ret = 0;
 
-	/* do not allow allocations/frees/init while we iterate */
-	rte_rwlock_read_lock(&mcfg->memory_hotplug_lock);
-
 	for (i = 0; i < RTE_MAX_MEMSEG_LISTS; i++) {
 		struct rte_memseg_list *msl = &mcfg->memsegs[i];
 		const struct rte_memseg *ms;
@@ -863,18 +860,25 @@  rte_memseg_walk(rte_memseg_walk_t func, void *arg)
 		while (ms_idx >= 0) {
 			ms = rte_fbarray_get(arr, ms_idx);
 			ret = func(msl, ms, arg);
-			if (ret < 0) {
-				ret = -1;
-				goto out;
-			} else if (ret > 0) {
-				ret = 1;
-				goto out;
-			}
+			if (ret)
+				return ret;
 			ms_idx = rte_fbarray_find_next_used(arr, ms_idx + 1);
 		}
 	}
-out:
+	return 0;
+}
+
+int __rte_experimental
+rte_memseg_walk(rte_memseg_walk_t func, void *arg)
+{
+	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
+	int ret = 0;
+
+	/* do not allow allocations/frees/init while we iterate */
+	rte_rwlock_read_lock(&mcfg->memory_hotplug_lock);
+	ret = rte_memseg_walk_thread_unsafe(func, arg);
 	rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
+
 	return ret;
 }
 
diff --git a/lib/librte_eal/common/include/rte_memory.h b/lib/librte_eal/common/include/rte_memory.h
index aeba38bfa..c5a84c333 100644
--- a/lib/librte_eal/common/include/rte_memory.h
+++ b/lib/librte_eal/common/include/rte_memory.h
@@ -263,6 +263,24 @@  rte_memseg_contig_walk(rte_memseg_contig_walk_t func, void *arg);
 int __rte_experimental
 rte_memseg_list_walk(rte_memseg_list_walk_t func, void *arg);
 
+/**
+ * Walk list of all memsegs without performing any locking.
+ *
+ * @note This function does not perform any locking, and is only safe to call
+ *       from within memory-related callback functions.
+ *
+ * @param func
+ *   Iterator function
+ * @param arg
+ *   Argument passed to iterator
+ * @return
+ *   0 if walked over the entire list
+ *   1 if stopped by the user
+ *   -1 if user function reported error
+ */
+int __rte_experimental
+rte_memseg_walk_thread_unsafe(rte_memseg_walk_t func, void *arg);
+
 /**
  * Walk each VA-contiguous area without performing any locking.
  *
diff --git a/lib/librte_eal/linuxapp/eal/eal_vfio.c b/lib/librte_eal/linuxapp/eal/eal_vfio.c
index a2bbdfbf4..14c9332e9 100644
--- a/lib/librte_eal/linuxapp/eal/eal_vfio.c
+++ b/lib/librte_eal/linuxapp/eal/eal_vfio.c
@@ -87,42 +87,6 @@  static const struct vfio_iommu_type iommu_types[] = {
 	},
 };
 
-/* for sPAPR IOMMU, we will need to walk memseg list, but we cannot use
- * rte_memseg_walk() because by the time we enter callback we will be holding a
- * write lock, so regular rte-memseg_walk will deadlock. copying the same
- * iteration code everywhere is not ideal as well. so, use a lockless copy of
- * memseg walk here.
- */
-static int
-memseg_walk_thread_unsafe(rte_memseg_walk_t func, void *arg)
-{
-	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
-	int i, ms_idx, ret = 0;
-
-	for (i = 0; i < RTE_MAX_MEMSEG_LISTS; i++) {
-		struct rte_memseg_list *msl = &mcfg->memsegs[i];
-		const struct rte_memseg *ms;
-		struct rte_fbarray *arr;
-
-		if (msl->memseg_arr.count == 0)
-			continue;
-
-		arr = &msl->memseg_arr;
-
-		ms_idx = rte_fbarray_find_next_used(arr, 0);
-		while (ms_idx >= 0) {
-			ms = rte_fbarray_get(arr, ms_idx);
-			ret = func(msl, ms, arg);
-			if (ret < 0)
-				return -1;
-			if (ret > 0)
-				return 1;
-			ms_idx = rte_fbarray_find_next_used(arr, ms_idx + 1);
-		}
-	}
-	return 0;
-}
-
 static int
 is_null_map(const struct user_mem_map *map)
 {
@@ -1357,7 +1321,8 @@  vfio_spapr_dma_mem_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
 	/* check if window size needs to be adjusted */
 	memset(&param, 0, sizeof(param));
 
-	if (memseg_walk_thread_unsafe(vfio_spapr_window_size_walk,
+	/* we're inside a callback so use thread-unsafe version */
+	if (rte_memseg_walk_thread_unsafe(vfio_spapr_window_size_walk,
 				&param) < 0) {
 		RTE_LOG(ERR, EAL, "Could not get window size\n");
 		ret = -1;
@@ -1386,7 +1351,9 @@  vfio_spapr_dma_mem_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
 				ret = -1;
 				goto out;
 			}
-			if (memseg_walk_thread_unsafe(vfio_spapr_map_walk,
+			/* we're inside a callback, so use thread-unsafe version
+			 */
+			if (rte_memseg_walk_thread_unsafe(vfio_spapr_map_walk,
 					&vfio_container_fd) < 0) {
 				RTE_LOG(ERR, EAL, "Could not recreate DMA maps\n");
 				ret = -1;
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index 98bfbe796..72d32fc39 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -289,6 +289,7 @@  EXPERIMENTAL {
 	rte_memseg_contig_walk_thread_unsafe;
 	rte_memseg_list_walk;
 	rte_memseg_walk;
+	rte_memseg_walk_thread_unsafe;
 	rte_mp_action_register;
 	rte_mp_action_unregister;
 	rte_mp_reply;