[dpdk-dev] [PATCH v1] common/mlx5: fix mlx5 aligned malloc

[dpdk-dev] [PATCH v1] common/mlx5: fix mlx5 aligned malloc

[Ophir Munk]

Before this commit system call memalign was used for aligned
allocations, however memalign is deprecated.

Based on (1) - POSIX requires that memory aligned allocations can be
freed using free. Some systems provide no way to reclaim memory
allocated with memalign (because one can only pass to free a pointer
gotten from malloc, while, memalign would call malloc and then align the
obtained value).
Another issue is that 64/32 bits architectures use a minimal alignment
size. So any requested alignment below the minimal system size can be
simplified by calling malloc.

The glibc implementation allows memory obtained from posix_memalign to
be reclaimed with free.  This commit replaces system call memalign with
system call posix_memalign. It also calls malloc in case the requested
alignment is below the minimal system size.

(1) https://linux.die.net/man/3/memalign

Fixes: d38e3d526657 ("common/mlx5: add memory management functions")
Cc: stable@dpdk.org

Signed-off-by: Ophir Munk <ophirmu@nvidia.com>
Acked-by: Matan Azrad <matan@mellanox.com>
---
 drivers/common/mlx5/mlx5_malloc.c | 13 +++++++++----
 drivers/common/mlx5/mlx5_malloc.h |  8 ++++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/common/mlx5/mlx5_malloc.c b/drivers/common/mlx5/mlx5_malloc.c
index 316305d..4489971 100644
--- a/drivers/common/mlx5/mlx5_malloc.c
+++ b/drivers/common/mlx5/mlx5_malloc.c
@@ -151,9 +151,14 @@ static void *
 mlx5_alloc_align(size_t size, unsigned int align, unsigned int zero)
 {
 	void *buf;
-	buf = memalign(align, size);
-	if (!buf) {
-		DRV_LOG(ERR, "Couldn't allocate buf.\n");
+	int ret;
+
+	ret = posix_memalign(&buf, align, size);
+	if (ret) {
+		DRV_LOG(ERR,
+			"Couldn't allocate buf size=%zu align=%u. Err=%d\n",
+			size, align, ret);
+
 		return NULL;
 	}
 	if (zero)
@@ -190,7 +195,7 @@ mlx5_malloc(uint32_t flags, size_t size, unsigned int align, int socket)
 		return addr;
 	}
 	/* The memory will be allocated from system. */
-	if (align)
+	if (align > MLX5_MALLOC_ALIGNMENT)
 		addr = mlx5_alloc_align(size, align, !!(flags & MLX5_MEM_ZERO));
 	else if (flags & MLX5_MEM_ZERO)
 		addr = calloc(1, size);
diff --git a/drivers/common/mlx5/mlx5_malloc.h b/drivers/common/mlx5/mlx5_malloc.h
index d3e5f5b..8aea414 100644
--- a/drivers/common/mlx5/mlx5_malloc.h
+++ b/drivers/common/mlx5/mlx5_malloc.h
@@ -9,6 +9,14 @@
 extern "C" {
 #endif
 
+#ifndef MLX5_MALLOC_ALIGNMENT
+#ifndef RTE_ARCH_64
+#define MLX5_MALLOC_ALIGNMENT 8
+#else
+#define MLX5_MALLOC_ALIGNMENT 16
+#endif
+#endif
+
 enum mlx5_mem_flags {
 	MLX5_MEM_ANY = 0,
 	/* Memory will be allocated dpends on sys_mem_en. */
-- 
2.8.4

Re: [dpdk-dev] [PATCH v1] common/mlx5: fix mlx5 aligned malloc

[Raslan Darawsheh]

Hi,

> -----Original Message-----
> From: Ophir Munk <ophirmu@nvidia.com>
> Sent: Wednesday, September 9, 2020 11:43 AM
> To: dev@dpdk.org
> Cc: Raslan Darawsheh <rasland@nvidia.com>; Ophir Munk
> <ophirmu@nvidia.com>; Matan Azrad <matan@nvidia.com>;
> stable@dpdk.org
> Subject: [PATCH v1] common/mlx5: fix mlx5 aligned malloc
> 
> Before this commit system call memalign was used for aligned
> allocations, however memalign is deprecated.
> 
> Based on (1) - POSIX requires that memory aligned allocations can be
> freed using free. Some systems provide no way to reclaim memory
> allocated with memalign (because one can only pass to free a pointer
> gotten from malloc, while, memalign would call malloc and then align the
> obtained value).
> Another issue is that 64/32 bits architectures use a minimal alignment
> size. So any requested alignment below the minimal system size can be
> simplified by calling malloc.
> 
> The glibc implementation allows memory obtained from posix_memalign to
> be reclaimed with free.  This commit replaces system call memalign with
> system call posix_memalign. It also calls malloc in case the requested
> alignment is below the minimal system size.
> 
> (1)
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flinux
> .die.net%2Fman%2F3%2Fmemalign&amp;data=02%7C01%7Crasland%40nvid
> ia.com%7C28fa36f0f5544ee01f4a08d8549c7c57%7C43083d15727340c1b7db39
> efd9ccc17a%7C0%7C0%7C637352378361232944&amp;sdata=T73x%2FmnZHK
> 3Yl9fI17Orar%2FpCoXtHpQzZvdy47OckxA%3D&amp;reserved=0
> 
> Fixes: d38e3d526657 ("common/mlx5: add memory management functions")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ophir Munk <ophirmu@nvidia.com>
> Acked-by: Matan Azrad <matan@mellanox.com>
> ---
>  drivers/common/mlx5/mlx5_malloc.c | 13 +++++++++----
>  drivers/common/mlx5/mlx5_malloc.h |  8 ++++++++
>  2 files changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/common/mlx5/mlx5_malloc.c
> b/drivers/common/mlx5/mlx5_malloc.c
> index 316305d..4489971 100644
> --- a/drivers/common/mlx5/mlx5_malloc.c
> +++ b/drivers/common/mlx5/mlx5_malloc.c
> @@ -151,9 +151,14 @@ static void *
>  mlx5_alloc_align(size_t size, unsigned int align, unsigned int zero)
>  {
>  	void *buf;
> -	buf = memalign(align, size);
> -	if (!buf) {
> -		DRV_LOG(ERR, "Couldn't allocate buf.\n");
> +	int ret;
> +
> +	ret = posix_memalign(&buf, align, size);
> +	if (ret) {
> +		DRV_LOG(ERR,
> +			"Couldn't allocate buf size=%zu align=%u. Err=%d\n",
> +			size, align, ret);
> +
>  		return NULL;
>  	}
>  	if (zero)
> @@ -190,7 +195,7 @@ mlx5_malloc(uint32_t flags, size_t size, unsigned int
> align, int socket)
>  		return addr;
>  	}
>  	/* The memory will be allocated from system. */
> -	if (align)
> +	if (align > MLX5_MALLOC_ALIGNMENT)
>  		addr = mlx5_alloc_align(size, align, !!(flags &
> MLX5_MEM_ZERO));
>  	else if (flags & MLX5_MEM_ZERO)
>  		addr = calloc(1, size);
> diff --git a/drivers/common/mlx5/mlx5_malloc.h
> b/drivers/common/mlx5/mlx5_malloc.h
> index d3e5f5b..8aea414 100644
> --- a/drivers/common/mlx5/mlx5_malloc.h
> +++ b/drivers/common/mlx5/mlx5_malloc.h
> @@ -9,6 +9,14 @@
>  extern "C" {
>  #endif
> 
> +#ifndef MLX5_MALLOC_ALIGNMENT
> +#ifndef RTE_ARCH_64
> +#define MLX5_MALLOC_ALIGNMENT 8
> +#else
> +#define MLX5_MALLOC_ALIGNMENT 16
> +#endif
> +#endif
> +
>  enum mlx5_mem_flags {
>  	MLX5_MEM_ANY = 0,
>  	/* Memory will be allocated dpends on sys_mem_en. */
> --
> 2.8.4

Patch applied to next-net-mlx,

Kindest regards,
Raslan Darawsheh