[PATCH 1/2] eal: add stailq safe iterator macro

[PATCH 1/2] eal: add stailq safe iterator macro

[Sergio Gonzalez Monroy]

Removing/freeing elements elements within a STAILQ_FOREACH loop
is not safe. FreeBSD defines STAILQ_FOREACH_SAFE macro, which permits
these operations safely.

This patch defines this macro for Linux systems, where it is not defined.

Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
---

NOTE: This patch is based on top of:
	http://dpdk.org/dev/patchwork/patch/14995/

 lib/librte_eal/common/include/rte_tailq.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/librte_eal/common/include/rte_tailq.h b/lib/librte_eal/common/include/rte_tailq.h
index cc3c0f1..bba2835 100644
--- a/lib/librte_eal/common/include/rte_tailq.h
+++ b/lib/librte_eal/common/include/rte_tailq.h
@@ -163,6 +163,13 @@ void __attribute__((constructor, used)) tailqinitfn_ ##t(void) \
 	    (var) = (tvar))
 #endif
 
+#ifndef SLIST_FOREACH_SAFE
+#define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
+	for ((var) = SLIST_FIRST((head));                               \
+	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
+	    (var) = (tvar))
+#endif
+
 #ifdef __cplusplus
 }
 #endif
-- 
2.4.11

[PATCH 2/2] mempool: fix unsafe tailq element removal

[Sergio Gonzalez Monroy]

Potentially user provided function could remove/free tailq elements.
Doing so within a TAILQ_FOREACH loop is not safe.

Use _SAFE versions of _FOREACH macros.

Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
---
 lib/librte_mempool/rte_mempool.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index 8806633..394154a 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -157,10 +157,10 @@ rte_mempool_obj_iter(struct rte_mempool *mp,
 	rte_mempool_obj_cb_t *obj_cb, void *obj_cb_arg)
 {
 	struct rte_mempool_objhdr *hdr;
-	void *obj;
+	void *obj, *temp;
 	unsigned n = 0;
 
-	STAILQ_FOREACH(hdr, &mp->elt_list, next) {
+	STAILQ_FOREACH_SAFE(hdr, &mp->elt_list, next, temp) {
 		obj = (char *)hdr + sizeof(*hdr);
 		obj_cb(mp, obj_cb_arg, obj, n);
 		n++;
@@ -176,8 +176,9 @@ rte_mempool_mem_iter(struct rte_mempool *mp,
 {
 	struct rte_mempool_memhdr *hdr;
 	unsigned n = 0;
+	void *temp;
 
-	STAILQ_FOREACH(hdr, &mp->mem_list, next) {
+	STAILQ_FOREACH_SAFE(hdr, &mp->mem_list, next, temp) {
 		mem_cb(mp, mem_cb_arg, hdr, n);
 		n++;
 	}
@@ -1283,12 +1284,13 @@ void rte_mempool_walk(void (*func)(struct rte_mempool *, void *),
 {
 	struct rte_tailq_entry *te = NULL;
 	struct rte_mempool_list *mempool_list;
+	void *temp;
 
 	mempool_list = RTE_TAILQ_CAST(rte_mempool_tailq.head, rte_mempool_list);
 
 	rte_rwlock_read_lock(RTE_EAL_MEMPOOL_RWLOCK);
 
-	TAILQ_FOREACH(te, mempool_list, next) {
+	TAILQ_FOREACH_SAFE(te, mempool_list, next, temp) {
 		(*func)((struct rte_mempool *) te->data, arg);
 	}
 
-- 
2.4.11

Re: [PATCH 1/2] eal: add stailq safe iterator macro

[Thomas Monjalon]

2016-07-22 17:01, Sergio Gonzalez Monroy:
> Removing/freeing elements elements within a STAILQ_FOREACH loop
> is not safe. FreeBSD defines STAILQ_FOREACH_SAFE macro, which permits
> these operations safely.
> 
> This patch defines this macro for Linux systems, where it is not defined.
[...]
> +#ifndef SLIST_FOREACH_SAFE
> +#define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
> +	for ((var) = SLIST_FIRST((head));                               \
> +	    (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
> +	    (var) = (tvar))
> +#endif

The patch 2 requires STAILQ_FOREACH_SAFE, not SLIST_FOREACH_SAFE.

Re: [PATCH 2/2] mempool: fix unsafe tailq element removal

[Olivier Matz]

Hi Sergio,

On 07/22/2016 06:01 PM, Sergio Gonzalez Monroy wrote:
> Potentially user provided function could remove/free tailq elements.
> Doing so within a TAILQ_FOREACH loop is not safe.
> 
> Use _SAFE versions of _FOREACH macros.
> 
> Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
> ---
>  lib/librte_mempool/rte_mempool.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index 8806633..394154a 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -157,10 +157,10 @@ rte_mempool_obj_iter(struct rte_mempool *mp,
>  	rte_mempool_obj_cb_t *obj_cb, void *obj_cb_arg)
>  {
>  	struct rte_mempool_objhdr *hdr;
> -	void *obj;
> +	void *obj, *temp;
>  	unsigned n = 0;
>  
> -	STAILQ_FOREACH(hdr, &mp->elt_list, next) {
> +	STAILQ_FOREACH_SAFE(hdr, &mp->elt_list, next, temp) {
>  		obj = (char *)hdr + sizeof(*hdr);
>  		obj_cb(mp, obj_cb_arg, obj, n);
>  		n++;
> @@ -176,8 +176,9 @@ rte_mempool_mem_iter(struct rte_mempool *mp,
>  {
>  	struct rte_mempool_memhdr *hdr;
>  	unsigned n = 0;
> +	void *temp;
>  
> -	STAILQ_FOREACH(hdr, &mp->mem_list, next) {
> +	STAILQ_FOREACH_SAFE(hdr, &mp->mem_list, next, temp) {
>  		mem_cb(mp, mem_cb_arg, hdr, n);
>  		n++;
>  	}

Not sure it is required to use the _SAFE() variant here.
The object or mem_chunk should be considered as const, because these
objects are not allocated/freed by the user but by the mempool functions.

> @@ -1283,12 +1284,13 @@ void rte_mempool_walk(void (*func)(struct rte_mempool *, void *),
>  {
>  	struct rte_tailq_entry *te = NULL;
>  	struct rte_mempool_list *mempool_list;
> +	void *temp;
>  
>  	mempool_list = RTE_TAILQ_CAST(rte_mempool_tailq.head, rte_mempool_list);
>  
>  	rte_rwlock_read_lock(RTE_EAL_MEMPOOL_RWLOCK);
>  
> -	TAILQ_FOREACH(te, mempool_list, next) {
> +	TAILQ_FOREACH_SAFE(te, mempool_list, next, temp) {
>  		(*func)((struct rte_mempool *) te->data, arg);
>  	}
>  
> 

I think this one is legitimate and we should have it for 16.07.
So only this hunk would be required, and the patch 1/2 may be dropped if
we remove the first 2 chunks.

Regards,
Olivier

[PATCH v2] mempool: fix unsafe removal from list by callback

[Thomas Monjalon]

If a mempool is removed from the list by a callback function
during rte_mempool_walk(), the TAILQ_FOREACH loop will fail unexpectedly.
It is fixed by using the safe version of the loop macro.

Reported-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
---
 lib/librte_mempool/rte_mempool.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index 8806633..2e28e2e 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -1283,12 +1283,13 @@ void rte_mempool_walk(void (*func)(struct rte_mempool *, void *),
 {
 	struct rte_tailq_entry *te = NULL;
 	struct rte_mempool_list *mempool_list;
+	void *tmp_te;
 
 	mempool_list = RTE_TAILQ_CAST(rte_mempool_tailq.head, rte_mempool_list);
 
 	rte_rwlock_read_lock(RTE_EAL_MEMPOOL_RWLOCK);
 
-	TAILQ_FOREACH(te, mempool_list, next) {
+	TAILQ_FOREACH_SAFE(te, mempool_list, next, tmp_te) {
 		(*func)((struct rte_mempool *) te->data, arg);
 	}
 
-- 
2.7.0

Re: [PATCH v2] mempool: fix unsafe removal from list by callback

[Olivier Matz]

Hello Thomas,

On 07/25/2016 09:54 PM, Thomas Monjalon wrote:
> If a mempool is removed from the list by a callback function
> during rte_mempool_walk(), the TAILQ_FOREACH loop will fail unexpectedly.
> It is fixed by using the safe version of the loop macro.
> 
> Reported-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
> Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
> ---
>  lib/librte_mempool/rte_mempool.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index 8806633..2e28e2e 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -1283,12 +1283,13 @@ void rte_mempool_walk(void (*func)(struct rte_mempool *, void *),
>  {
>  	struct rte_tailq_entry *te = NULL;
>  	struct rte_mempool_list *mempool_list;
> +	void *tmp_te;
>  
>  	mempool_list = RTE_TAILQ_CAST(rte_mempool_tailq.head, rte_mempool_list);
>  
>  	rte_rwlock_read_lock(RTE_EAL_MEMPOOL_RWLOCK);
>  
> -	TAILQ_FOREACH(te, mempool_list, next) {
> +	TAILQ_FOREACH_SAFE(te, mempool_list, next, tmp_te) {
>  		(*func)((struct rte_mempool *) te->data, arg);
>  	}
>  
> 

Acked-by: Olivier Matz <olivier.matz@6wind.com>

Thanks

Re: [PATCH v2] mempool: fix unsafe removal from list by callback

[Thomas Monjalon]

> > If a mempool is removed from the list by a callback function
> > during rte_mempool_walk(), the TAILQ_FOREACH loop will fail unexpectedly.
> > It is fixed by using the safe version of the loop macro.
> > 
> > Reported-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
> > Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
> 
> Acked-by: Olivier Matz <olivier.matz@6wind.com>

Applied, thanks