During memory initialization calling rte_mem_check_dma_mask
leads to a deadlock because memory_hotplug_lock is locked by a
writer, the current code in execution, and rte_memseg_walk
tries to lock as a reader.
This patch adds a thread_unsafe version which will call the final
function specifying the memory_hotplug_lock does not need to be
acquired. The patch also modified rte_mem_check_dma_mask as a
intermediate step which will call the final function as before,
implying memory_hotplug_lock will be acquired.
PMDs should always use the version acquiring the lock with the
thread_unsafe one being just for internal EAL memory code.
Fixes: 223b7f1d5ef6 ("mem: add function for checking memseg IOVA")
Signed-off-by: Alejandro Lucero <alejandro.luc...@netronome.com>
---
lib/librte_eal/common/eal_common_memory.c | 24 +++++++++++++--
lib/librte_eal/common/include/rte_memory.h | 35 +++++++++++++++++++---
lib/librte_eal/common/malloc_heap.c | 2 +-
lib/librte_eal/linuxapp/eal/eal_memory.c | 4 +--
lib/librte_eal/rte_eal_version.map | 1 +
5 files changed, 56 insertions(+), 10 deletions(-)
diff --git a/lib/librte_eal/common/eal_common_memory.c
b/lib/librte_eal/common/eal_common_memory.c
index cc4f1d80f..87fd9921f 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -446,11 +446,12 @@ check_iova(const struct rte_memseg_list *msl __rte_unused,
#endif
/* check memseg iovas are within the required range based on dma mask */
-int __rte_experimental
-rte_mem_check_dma_mask(uint8_t maskbits)
+static int __rte_experimental
+check_dma_mask(uint8_t maskbits, bool thread_unsafe)
{
struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
uint64_t mask;
+ int ret;
/* sanity check */
if (maskbits > MAX_DMA_MASK_BITS) {
@@ -462,7 +463,12 @@ rte_mem_check_dma_mask(uint8_t maskbits)
/* create dma mask */
mask = ~((1ULL << maskbits) - 1);
- if (rte_memseg_walk(check_iova, &mask))
+ if (thread_unsafe)
+ ret = rte_memseg_walk_thread_unsafe(check_iova, &mask);
+ else
+ ret = rte_memseg_walk(check_iova, &mask);
+
+ if (ret)
/*
* Dma mask precludes hugepage usage.
* This device can not be used and we do not need to keep
@@ -480,6 +486,18 @@ rte_mem_check_dma_mask(uint8_t maskbits)
return 0;
}
+int __rte_experimental
+rte_mem_check_dma_mask(uint8_t maskbits)
+{
+ return check_dma_mask(maskbits, false);
+}
+
+int __rte_experimental
+rte_mem_check_dma_mask_thread_unsafe(uint8_t maskbits)
+{
+ return check_dma_mask(maskbits, true);
+}
+
/*
* Set dma mask to use when memory initialization is done.
*
diff --git a/lib/librte_eal/common/include/rte_memory.h
b/lib/librte_eal/common/include/rte_memory.h
index abbfe2364..d970825df 100644
--- a/lib/librte_eal/common/include/rte_memory.h
+++ b/lib/librte_eal/common/include/rte_memory.h
@@ -463,16 +463,43 @@ unsigned rte_memory_get_nchannel(void);
*/
unsigned rte_memory_get_nrank(void);
-/* check memsegs iovas are within a range based on dma mask */
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Check if all currently allocated memory segments are compliant with
+ * supplied DMA address width.
+ *
+ * @param maskbits
+ * Address width to check against.
+ */
int __rte_experimental rte_mem_check_dma_mask(uint8_t maskbits);
/**
* @warning
* @b EXPERIMENTAL: this API may change without prior notice
*
- * Set dma mask to use once memory initialization is done.
- * Previous function rte_mem_check_dma_mask can not be used
- * safely until memory has been initialized.
+ * Check if all currently allocated memory segments are compliant with
+ * supplied DMA address width. This function will use
+ * rte_memseg_walk_thread_unsafe instead of rte_memseg_walk implying
+ * memory_hotplug_lock will not be acquired avoiding deadlock during
+ * memory initialization.
+ *
+ * This function is just for EAL core memory internal use. Drivers should
+ * use the previous rte_mem_check_dma_mask.
+ *
+ * @param maskbits
+ * Address width to check against.
+ */
+int __rte_experimental rte_mem_check_dma_mask_thread_unsafe(uint8_t maskbits);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Set dma mask to use once memory initialization is done. Previous functions
+ * rte_mem_check_dma_mask and rte_mem_check_dma_mask_thread_unsafe can not be
+ * used safely until memory has been initialized.
*/
void __rte_experimental rte_mem_set_dma_mask(uint8_t maskbits);
diff --git a/lib/librte_eal/common/malloc_heap.c
b/lib/librte_eal/common/malloc_heap.c
index c2c112aa6..c6a6d4f6b 100644
--- a/lib/librte_eal/common/malloc_heap.c
+++ b/lib/librte_eal/common/malloc_heap.c
@@ -334,7 +334,7 @@ alloc_pages_on_heap(struct malloc_heap *heap, uint64_t
pg_sz, size_t elt_size,
* executed. For 2) implies the new memory can not be added.
*/
if (mcfg->dma_maskbits &&
- rte_mem_check_dma_mask(mcfg->dma_maskbits)) {
+ rte_mem_check_dma_mask_thread_unsafe(mcfg->dma_maskbits)) {
/*
* Currently this can only happen if IOMMU is enabled
* and the address width supported by the IOMMU hw is
diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
b/lib/librte_eal/linuxapp/eal/eal_memory.c
index c7935879a..c1b5e0791 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -1394,7 +1394,7 @@ eal_legacy_hugepage_init(void)
addr = RTE_PTR_ADD(addr, (size_t)page_sz);
}
if (mcfg->dma_maskbits &&
- rte_mem_check_dma_mask(mcfg->dma_maskbits)) {
+ rte_mem_check_dma_mask_thread_unsafe(mcfg->dma_maskbits)) {
RTE_LOG(ERR, EAL,
"%s(): couldnt allocate memory due to IOVA
exceeding limits of current DMA mask.\n",
__func__);
@@ -1641,7 +1641,7 @@ eal_legacy_hugepage_init(void)
}
if (mcfg->dma_maskbits &&
- rte_mem_check_dma_mask(mcfg->dma_maskbits)) {
+ rte_mem_check_dma_mask_thread_unsafe(mcfg->dma_maskbits)) {
RTE_LOG(ERR, EAL,
"%s(): couldn't allocate memory due to IOVA exceeding
limits of current DMA mask.\n",
__func__);
diff --git a/lib/librte_eal/rte_eal_version.map
b/lib/librte_eal/rte_eal_version.map
index 51ee948ba..61bc5ca05 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -331,6 +331,7 @@ EXPERIMENTAL {
rte_mem_alloc_validator_register;
rte_mem_alloc_validator_unregister;
rte_mem_check_dma_mask;
+ rte_mem_check_dma_mask_thread_unsafe;
rte_mem_event_callback_register;
rte_mem_event_callback_unregister;
rte_mem_iova2virt;
--
2.17.1
