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* [dpdk-dev] [PATCH] lib/librte_timer:fix corruption with reset
@ 2020-07-07  9:03 Sarosh Arif
  2020-07-07 16:09 ` Stephen Hemminger
                   ` (2 more replies)
  0 siblings, 3 replies; 10+ messages in thread
From: Sarosh Arif @ 2020-07-07  9:03 UTC (permalink / raw)
  To: rsanford, erik.g.carrillo, dev; +Cc: stable, Sarosh Arif, h.mikita89

If the user tries to reset/stop some other timer in it's callback
function, which is also about to expire, using 
rte_timer_reset_sync/rte_timer_stop_sync the application goes into
an infinite loop. This happens because 
rte_timer_reset_sync/rte_timer_stop_sync loop until the timer 
resets/stops and there is check inside timer_set_config_state which
prevents a running timer from being reset/stopped by not it's own 
timer_cb. Therefore timer_set_config_state returns -1 due to which 
rte_timer_reset returns -1 and rte_timer_reset_sync goes into an 
infinite loop. 

The soloution to this problem is to return -1 from 
rte_timer_reset_sync/rte_timer_stop_sync in case the user tries to 
reset/stop some other timer in it's callback function.

Bugzilla ID: 491
Fixes: 20d159f20543 ("timer: fix corruption with reset")
Cc: h.mikita89@gmail.com
Signed-off-by: Sarosh Arif <sarosh.arif@emumba.com>
---
 lib/librte_timer/rte_timer.c | 25 +++++++++++++++++++++++--
 lib/librte_timer/rte_timer.h |  4 ++--
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/lib/librte_timer/rte_timer.c b/lib/librte_timer/rte_timer.c
index 6d19ce469..ed48bcbfd 100644
--- a/lib/librte_timer/rte_timer.c
+++ b/lib/librte_timer/rte_timer.c
@@ -576,14 +576,24 @@ rte_timer_alt_reset(uint32_t timer_data_id, struct rte_timer *tim,
 }
 
 /* loop until rte_timer_reset() succeed */
-void
+int
 rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
 		     enum rte_timer_type type, unsigned tim_lcore,
 		     rte_timer_cb_t fct, void *arg)
 {
+	struct rte_timer_data *timer_data;
+	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);
+
+	if (tim->status.state == RTE_TIMER_RUNNING &&	\
+	(tim->status.owner != (uint16_t)tim_lcore ||	\
+	tim != timer_data->priv_timer[tim_lcore].running_tim))
+		return -1;
+
 	while (rte_timer_reset(tim, ticks, type, tim_lcore,
 			       fct, arg) != 0)
 		rte_pause();
+
+	return 0;
 }
 
 static int
@@ -642,11 +652,22 @@ rte_timer_alt_stop(uint32_t timer_data_id, struct rte_timer *tim)
 }
 
 /* loop until rte_timer_stop() succeed */
-void
+int
 rte_timer_stop_sync(struct rte_timer *tim)
 {
+	struct rte_timer_data *timer_data;
+	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);
+	unsigned int lcore_id = rte_lcore_id();
+
+	if (tim->status.state == RTE_TIMER_RUNNING &&	\
+	(tim->status.owner != (uint16_t)lcore_id ||	\
+	tim != timer_data->priv_timer[lcore_id].running_tim))
+		return -1;
+
 	while (rte_timer_stop(tim) != 0)
 		rte_pause();
+
+	return 0;
 }
 
 /* Test the PENDING status of the timer handle tim */
diff --git a/lib/librte_timer/rte_timer.h b/lib/librte_timer/rte_timer.h
index c6b3d450d..392ca423d 100644
--- a/lib/librte_timer/rte_timer.h
+++ b/lib/librte_timer/rte_timer.h
@@ -275,7 +275,7 @@ int rte_timer_reset(struct rte_timer *tim, uint64_t ticks,
  * @param arg
  *   The user argument of the callback function.
  */
-void
+int
 rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
 		     enum rte_timer_type type, unsigned tim_lcore,
 		     rte_timer_cb_t fct, void *arg);
@@ -314,7 +314,7 @@ int rte_timer_stop(struct rte_timer *tim);
  * @param tim
  *   The timer handle.
  */
-void rte_timer_stop_sync(struct rte_timer *tim);
+int rte_timer_stop_sync(struct rte_timer *tim);
 
 /**
  * Test if a timer is pending.
-- 
2.17.1


^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [dpdk-dev] [PATCH] lib/librte_timer:fix corruption with reset
  2020-07-07  9:03 [dpdk-dev] [PATCH] lib/librte_timer:fix corruption with reset Sarosh Arif
@ 2020-07-07 16:09 ` Stephen Hemminger
  2020-07-08  5:06 ` [dpdk-dev] [PATCH v2] " Sarosh Arif
  2020-07-10  6:59 ` [dpdk-dev] [PATCH v3] " Sarosh Arif
  2 siblings, 0 replies; 10+ messages in thread
From: Stephen Hemminger @ 2020-07-07 16:09 UTC (permalink / raw)
  To: Sarosh Arif; +Cc: rsanford, erik.g.carrillo, dev, stable, h.mikita89

On Tue,  7 Jul 2020 14:03:20 +0500
Sarosh Arif <sarosh.arif@emumba.com> wrote:

> +	struct rte_timer_data *timer_data;
> +	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);
> +
> +	if (tim->status.state == RTE_TIMER_RUNNING &&	\
> +	(tim->status.owner != (uint16_t)tim_lcore ||	\
> +	tim != timer_data->priv_timer[tim_lcore].running_tim))
> +		return -1;
> +

This is code not a macro.
Look at checkpatch output, no \ in code.

^ permalink raw reply	[flat|nested] 10+ messages in thread

* [dpdk-dev] [PATCH v2] lib/librte_timer:fix corruption with reset
  2020-07-07  9:03 [dpdk-dev] [PATCH] lib/librte_timer:fix corruption with reset Sarosh Arif
  2020-07-07 16:09 ` Stephen Hemminger
@ 2020-07-08  5:06 ` Sarosh Arif
  2020-07-08 15:07   ` Stephen Hemminger
  2020-07-08 15:08   ` Stephen Hemminger
  2020-07-10  6:59 ` [dpdk-dev] [PATCH v3] " Sarosh Arif
  2 siblings, 2 replies; 10+ messages in thread
From: Sarosh Arif @ 2020-07-08  5:06 UTC (permalink / raw)
  To: rsanford, erik.g.carrillo, dev; +Cc: stable, Sarosh Arif, h.mikita89

If the user tries to reset/stop some other timer in it's callback
function, which is also about to expire, using 
rte_timer_reset_sync/rte_timer_stop_sync the application goes into
an infinite loop. This happens because 
rte_timer_reset_sync/rte_timer_stop_sync loop until the timer 
resets/stops and there is check inside timer_set_config_state which
prevents a running timer from being reset/stopped by not it's own 
timer_cb. Therefore timer_set_config_state returns -1 due to which 
rte_timer_reset returns -1 and rte_timer_reset_sync goes into an 
infinite loop. 

The soloution to this problem is to return -1 from 
rte_timer_reset_sync/rte_timer_stop_sync in case the user tries to 
reset/stop some other timer in it's callback function.

Bugzilla ID: 491
Fixes: 20d159f20543 ("timer: fix corruption with reset")
Cc: h.mikita89@gmail.com
Signed-off-by: Sarosh Arif <sarosh.arif@emumba.com>
---
v2: remove line continuations
---
 lib/librte_timer/rte_timer.c | 25 +++++++++++++++++++++++--
 lib/librte_timer/rte_timer.h |  4 ++--
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/lib/librte_timer/rte_timer.c b/lib/librte_timer/rte_timer.c
index 6d19ce469..be86385a1 100644
--- a/lib/librte_timer/rte_timer.c
+++ b/lib/librte_timer/rte_timer.c
@@ -576,14 +576,24 @@ rte_timer_alt_reset(uint32_t timer_data_id, struct rte_timer *tim,
 }
 
 /* loop until rte_timer_reset() succeed */
-void
+int
 rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
 		     enum rte_timer_type type, unsigned tim_lcore,
 		     rte_timer_cb_t fct, void *arg)
 {
+	struct rte_timer_data *timer_data;
+	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);
+
+	if (tim->status.state == RTE_TIMER_RUNNING &&
+	(tim->status.owner != (uint16_t)tim_lcore ||
+	tim != timer_data->priv_timer[tim_lcore].running_tim))
+		return -1;
+
 	while (rte_timer_reset(tim, ticks, type, tim_lcore,
 			       fct, arg) != 0)
 		rte_pause();
+
+	return 0;
 }
 
 static int
@@ -642,11 +652,22 @@ rte_timer_alt_stop(uint32_t timer_data_id, struct rte_timer *tim)
 }
 
 /* loop until rte_timer_stop() succeed */
-void
+int
 rte_timer_stop_sync(struct rte_timer *tim)
 {
+	struct rte_timer_data *timer_data;
+	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);
+	unsigned int lcore_id = rte_lcore_id();
+
+	if (tim->status.state == RTE_TIMER_RUNNING &&
+	(tim->status.owner != (uint16_t)lcore_id ||
+	tim != timer_data->priv_timer[lcore_id].running_tim))
+		return -1;
+
 	while (rte_timer_stop(tim) != 0)
 		rte_pause();
+
+	return 0;
 }
 
 /* Test the PENDING status of the timer handle tim */
diff --git a/lib/librte_timer/rte_timer.h b/lib/librte_timer/rte_timer.h
index c6b3d450d..392ca423d 100644
--- a/lib/librte_timer/rte_timer.h
+++ b/lib/librte_timer/rte_timer.h
@@ -275,7 +275,7 @@ int rte_timer_reset(struct rte_timer *tim, uint64_t ticks,
  * @param arg
  *   The user argument of the callback function.
  */
-void
+int
 rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
 		     enum rte_timer_type type, unsigned tim_lcore,
 		     rte_timer_cb_t fct, void *arg);
@@ -314,7 +314,7 @@ int rte_timer_stop(struct rte_timer *tim);
  * @param tim
  *   The timer handle.
  */
-void rte_timer_stop_sync(struct rte_timer *tim);
+int rte_timer_stop_sync(struct rte_timer *tim);
 
 /**
  * Test if a timer is pending.
-- 
2.17.1


^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [dpdk-dev] [PATCH v2] lib/librte_timer:fix corruption with reset
  2020-07-08  5:06 ` [dpdk-dev] [PATCH v2] " Sarosh Arif
@ 2020-07-08 15:07   ` Stephen Hemminger
  2020-07-09  7:05     ` Sarosh Arif
  2020-07-08 15:08   ` Stephen Hemminger
  1 sibling, 1 reply; 10+ messages in thread
From: Stephen Hemminger @ 2020-07-08 15:07 UTC (permalink / raw)
  To: Sarosh Arif; +Cc: rsanford, erik.g.carrillo, dev, stable, h.mikita89

On Wed,  8 Jul 2020 10:06:26 +0500
Sarosh Arif <sarosh.arif@emumba.com> wrote:

>  /* loop until rte_timer_reset() succeed */
> -void
> +int
>  rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
>  		     enum rte_timer_type type, unsigned tim_lcore,
>  		     rte_timer_cb_t fct, void *arg)

This is an API change and needs to wait until a breaking release like 20.11.
Also most applications won't test the result.

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [dpdk-dev] [PATCH v2] lib/librte_timer:fix corruption with reset
  2020-07-08  5:06 ` [dpdk-dev] [PATCH v2] " Sarosh Arif
  2020-07-08 15:07   ` Stephen Hemminger
@ 2020-07-08 15:08   ` Stephen Hemminger
  2020-07-09  7:02     ` Sarosh Arif
  1 sibling, 1 reply; 10+ messages in thread
From: Stephen Hemminger @ 2020-07-08 15:08 UTC (permalink / raw)
  To: Sarosh Arif; +Cc: rsanford, erik.g.carrillo, dev, stable, h.mikita89

On Wed,  8 Jul 2020 10:06:26 +0500
Sarosh Arif <sarosh.arif@emumba.com> wrote:

>  rte_timer_stop_sync(struct rte_timer *tim)
>  {
> +	struct rte_timer_data *timer_data;
> +	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);
> +	unsigned int lcore_id = rte_lcore_id();

This mixing code and declarations. since the macro has a return statement.

Maybe:

	struct rte_timer_data *timer_data;
	unsigned int lcore_id = rte_lcore_id();

	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [dpdk-dev] [PATCH v2] lib/librte_timer:fix corruption with reset
  2020-07-08 15:08   ` Stephen Hemminger
@ 2020-07-09  7:02     ` Sarosh Arif
  0 siblings, 0 replies; 10+ messages in thread
From: Sarosh Arif @ 2020-07-09  7:02 UTC (permalink / raw)
  To: Stephen Hemminger; +Cc: rsanford, erik.g.carrillo, dev, stable, h.mikita89

On Wed, Jul 8, 2020 at 8:08 PM Stephen Hemminger <stephen@networkplumber.org>
wrote:

> On Wed,  8 Jul 2020 10:06:26 +0500
> Sarosh Arif <sarosh.arif@emumba.com> wrote:
>
> >  rte_timer_stop_sync(struct rte_timer *tim)
> >  {
> > +     struct rte_timer_data *timer_data;
> > +     TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data,
> -EINVAL);
> > +     unsigned int lcore_id = rte_lcore_id();
>
> This mixing code and declarations. since the macro has a return statement.
>
> Maybe:
>
>         struct rte_timer_data *timer_data;
>         unsigned int lcore_id = rte_lcore_id();
>
>         TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data,
> -EINVAL);
>
I will fix this in the next version.

^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [dpdk-dev] [PATCH v2] lib/librte_timer:fix corruption with reset
  2020-07-08 15:07   ` Stephen Hemminger
@ 2020-07-09  7:05     ` Sarosh Arif
  0 siblings, 0 replies; 10+ messages in thread
From: Sarosh Arif @ 2020-07-09  7:05 UTC (permalink / raw)
  To: Stephen Hemminger; +Cc: rsanford, erik.g.carrillo, dev, stable, h.mikita89

On Wed, Jul 8, 2020 at 8:07 PM Stephen Hemminger <stephen@networkplumber.org>
wrote:

> On Wed,  8 Jul 2020 10:06:26 +0500
> Sarosh Arif <sarosh.arif@emumba.com> wrote:
>
> >  /* loop until rte_timer_reset() succeed */
> > -void
> > +int
> >  rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
> >                    enum rte_timer_type type, unsigned tim_lcore,
> >                    rte_timer_cb_t fct, void *arg)
>
> This is an API change and needs to wait until a breaking release like
> 20.11.
>
Okay,waiting till the next breaking release sounds fine to me.


> Also most applications won't test the result.
>

^ permalink raw reply	[flat|nested] 10+ messages in thread

* [dpdk-dev] [PATCH v3] lib/librte_timer:fix corruption with reset
  2020-07-07  9:03 [dpdk-dev] [PATCH] lib/librte_timer:fix corruption with reset Sarosh Arif
  2020-07-07 16:09 ` Stephen Hemminger
  2020-07-08  5:06 ` [dpdk-dev] [PATCH v2] " Sarosh Arif
@ 2020-07-10  6:59 ` Sarosh Arif
  2020-07-10 15:19   ` Stephen Hemminger
  2020-07-28 19:04   ` Carrillo, Erik G
  2 siblings, 2 replies; 10+ messages in thread
From: Sarosh Arif @ 2020-07-10  6:59 UTC (permalink / raw)
  To: rsanford, erik.g.carrillo, dev; +Cc: stable, Sarosh Arif, h.mikita89

If the user tries to reset/stop some other timer in it's callback
function, which is also about to expire, using 
rte_timer_reset_sync/rte_timer_stop_sync the application goes into
an infinite loop. This happens because 
rte_timer_reset_sync/rte_timer_stop_sync loop until the timer 
resets/stops and there is check inside timer_set_config_state which
prevents a running timer from being reset/stopped by not it's own 
timer_cb. Therefore timer_set_config_state returns -1 due to which 
rte_timer_reset returns -1 and rte_timer_reset_sync goes into an 
infinite loop. 

The soloution to this problem is to return -1 from 
rte_timer_reset_sync/rte_timer_stop_sync in case the user tries to 
reset/stop some other timer in it's callback function.

Bugzilla ID: 491
Fixes: 20d159f20543 ("timer: fix corruption with reset")
Cc: h.mikita89@gmail.com
Signed-off-by: Sarosh Arif <sarosh.arif@emumba.com>
---
v2: remove line continuations
v3: separate code and declarations
---
 lib/librte_timer/rte_timer.c | 26 ++++++++++++++++++++++++--
 lib/librte_timer/rte_timer.h |  4 ++--
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/lib/librte_timer/rte_timer.c b/lib/librte_timer/rte_timer.c
index 6d19ce469..0cd3e2c86 100644
--- a/lib/librte_timer/rte_timer.c
+++ b/lib/librte_timer/rte_timer.c
@@ -576,14 +576,24 @@ rte_timer_alt_reset(uint32_t timer_data_id, struct rte_timer *tim,
 }
 
 /* loop until rte_timer_reset() succeed */
-void
+int
 rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
 		     enum rte_timer_type type, unsigned tim_lcore,
 		     rte_timer_cb_t fct, void *arg)
 {
+	struct rte_timer_data *timer_data;
+	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);
+
+	if (tim->status.state == RTE_TIMER_RUNNING &&
+	(tim->status.owner != (uint16_t)tim_lcore ||
+	tim != timer_data->priv_timer[tim_lcore].running_tim))
+		return -1;
+
 	while (rte_timer_reset(tim, ticks, type, tim_lcore,
 			       fct, arg) != 0)
 		rte_pause();
+
+	return 0;
 }
 
 static int
@@ -642,11 +652,23 @@ rte_timer_alt_stop(uint32_t timer_data_id, struct rte_timer *tim)
 }
 
 /* loop until rte_timer_stop() succeed */
-void
+int
 rte_timer_stop_sync(struct rte_timer *tim)
 {
+	struct rte_timer_data *timer_data;
+	unsigned int lcore_id = rte_lcore_id();
+
+	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id, timer_data, -EINVAL);
+
+	if (tim->status.state == RTE_TIMER_RUNNING &&
+	(tim->status.owner != (uint16_t)lcore_id ||
+	tim != timer_data->priv_timer[lcore_id].running_tim))
+		return -1;
+
 	while (rte_timer_stop(tim) != 0)
 		rte_pause();
+
+	return 0;
 }
 
 /* Test the PENDING status of the timer handle tim */
diff --git a/lib/librte_timer/rte_timer.h b/lib/librte_timer/rte_timer.h
index c6b3d450d..392ca423d 100644
--- a/lib/librte_timer/rte_timer.h
+++ b/lib/librte_timer/rte_timer.h
@@ -275,7 +275,7 @@ int rte_timer_reset(struct rte_timer *tim, uint64_t ticks,
  * @param arg
  *   The user argument of the callback function.
  */
-void
+int
 rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
 		     enum rte_timer_type type, unsigned tim_lcore,
 		     rte_timer_cb_t fct, void *arg);
@@ -314,7 +314,7 @@ int rte_timer_stop(struct rte_timer *tim);
  * @param tim
  *   The timer handle.
  */
-void rte_timer_stop_sync(struct rte_timer *tim);
+int rte_timer_stop_sync(struct rte_timer *tim);
 
 /**
  * Test if a timer is pending.
-- 
2.17.1


^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [dpdk-dev] [PATCH v3] lib/librte_timer:fix corruption with reset
  2020-07-10  6:59 ` [dpdk-dev] [PATCH v3] " Sarosh Arif
@ 2020-07-10 15:19   ` Stephen Hemminger
  2020-07-28 19:04   ` Carrillo, Erik G
  1 sibling, 0 replies; 10+ messages in thread
From: Stephen Hemminger @ 2020-07-10 15:19 UTC (permalink / raw)
  To: Sarosh Arif; +Cc: rsanford, erik.g.carrillo, dev, stable, h.mikita89

On Fri, 10 Jul 2020 11:59:54 +0500
Sarosh Arif <sarosh.arif@emumba.com> wrote:

> If the user tries to reset/stop some other timer in it's callback
> function, which is also about to expire, using 
> rte_timer_reset_sync/rte_timer_stop_sync the application goes into
> an infinite loop. This happens because 
> rte_timer_reset_sync/rte_timer_stop_sync loop until the timer 
> resets/stops and there is check inside timer_set_config_state which
> prevents a running timer from being reset/stopped by not it's own 
> timer_cb. Therefore timer_set_config_state returns -1 due to which 
> rte_timer_reset returns -1 and rte_timer_reset_sync goes into an 
> infinite loop. 
> 
> The soloution to this problem is to return -1 from 
> rte_timer_reset_sync/rte_timer_stop_sync in case the user tries to 
> reset/stop some other timer in it's callback function.
> 
> Bugzilla ID: 491
> Fixes: 20d159f20543 ("timer: fix corruption with reset")
> Cc: h.mikita89@gmail.com
> Signed-off-by: Sarosh Arif <sarosh.arif@emumba.com>
> ---
> v2: remove line continuations
> v3: separate code and declarations

If you want to change the return value, you need to go through the steps
in the API/ABI policy. Maybe even symbol versioning.

Sorry, I know it is painful but we committed to the rules.
And changing the return value can never go to stable.


^ permalink raw reply	[flat|nested] 10+ messages in thread

* Re: [dpdk-dev] [PATCH v3] lib/librte_timer:fix corruption with reset
  2020-07-10  6:59 ` [dpdk-dev] [PATCH v3] " Sarosh Arif
  2020-07-10 15:19   ` Stephen Hemminger
@ 2020-07-28 19:04   ` Carrillo, Erik G
  1 sibling, 0 replies; 10+ messages in thread
From: Carrillo, Erik G @ 2020-07-28 19:04 UTC (permalink / raw)
  To: Sarosh Arif, dev, rsanford; +Cc: h.mikita89, Stephen Hemminger

Hi Sarosh,

Some comments in-line:

> -----Original Message-----
> From: Sarosh Arif <sarosh.arif@emumba.com>
> Sent: Friday, July 10, 2020 2:00 AM
> To: rsanford@akamai.com; Carrillo, Erik G <erik.g.carrillo@intel.com>;
> dev@dpdk.org
> Cc: stable@dpdk.org; Sarosh Arif <sarosh.arif@emumba.com>;
> h.mikita89@gmail.com
> Subject: [PATCH v3] lib/librte_timer:fix corruption with reset

The subject is misleading - perhaps wording closer to the title of the Bugzilla bug would be more helpful.

> 
> If the user tries to reset/stop some other timer in it's callback function, which
> is also about to expire, using rte_timer_reset_sync/rte_timer_stop_sync the
> application goes into an infinite loop. This happens because
> rte_timer_reset_sync/rte_timer_stop_sync loop until the timer resets/stops
> and there is check inside timer_set_config_state which prevents a running
> timer from being reset/stopped by not it's own timer_cb. Therefore
> timer_set_config_state returns -1 due to which rte_timer_reset returns -1
> and rte_timer_reset_sync goes into an infinite loop.
> 
> The soloution to this problem is to return -1 from
> rte_timer_reset_sync/rte_timer_stop_sync in case the user tries to
> reset/stop some other timer in it's callback function.
> 
> Bugzilla ID: 491
> Fixes: 20d159f20543 ("timer: fix corruption with reset")
> Cc: h.mikita89@gmail.com
> Signed-off-by: Sarosh Arif <sarosh.arif@emumba.com>
> ---
> v2: remove line continuations
> v3: separate code and declarations
> ---
>  lib/librte_timer/rte_timer.c | 26 ++++++++++++++++++++++++--
> lib/librte_timer/rte_timer.h |  4 ++--
>  2 files changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_timer/rte_timer.c b/lib/librte_timer/rte_timer.c index
> 6d19ce469..0cd3e2c86 100644
> --- a/lib/librte_timer/rte_timer.c
> +++ b/lib/librte_timer/rte_timer.c
> @@ -576,14 +576,24 @@ rte_timer_alt_reset(uint32_t timer_data_id, struct
> rte_timer *tim,  }
> 
>  /* loop until rte_timer_reset() succeed */ -void
> +int
>  rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
>  		     enum rte_timer_type type, unsigned tim_lcore,
>  		     rte_timer_cb_t fct, void *arg)
>  {
> +	struct rte_timer_data *timer_data;
> +	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id,
> timer_data, -EINVAL);
> +
> +	if (tim->status.state == RTE_TIMER_RUNNING &&
> +	(tim->status.owner != (uint16_t)tim_lcore ||
> +	tim != timer_data->priv_timer[tim_lcore].running_tim))
> +		return -1;
> +

As I understand it, Bugzilla 491 describes two scenarios where a hang can occur:
1.  A timer's callback tries to synchronously reset/stop another timer in the same run list
2.  A timer's callback tries to synchronously reset/stop another timer in a different run list whose lcore happens to be running a timer callback that is synchronously resetting/stopping a timer in the first run list

The if condition from the patch above can be broken up as:

	(tim->status.state == RTE_TIMER_RUNNING && tim->status.owner == (uint16_t)lcore_id && tim != timer_data->priv_timer[lcore_id].running_tim)

And

 	(tim->status.state == RTE_TIMER_RUNNING && tim->status.owner != (uint16_t)lcore_id)

This second condition could be transient and doesn't necessarily identify scenario (2) above.  In this case, the *_sync() calls could fail unnecessarily.

Offhand, I'm not seeing a way to more precisely detect scenario 2 above.  I'm wondering if some kind of a timeout parameter could be added to avoid hanging instead.  Thoughts?

As Stephen mentioned in another response, it looks like this will require an API change.  I believe this can be announced in the next release via doc/guides/rel_notes/deprecation.rst.  Then, the new API can be added in the next ABI-breaking release, possibly with versioned symbols (http://doc.dpdk.org/guides/contributing/abi_versioning.html#versioning-macros).  

Thanks,
Erik

>  	while (rte_timer_reset(tim, ticks, type, tim_lcore,
>  			       fct, arg) != 0)
>  		rte_pause();
> +
> +	return 0;
>  }
> 
>  static int
> @@ -642,11 +652,23 @@ rte_timer_alt_stop(uint32_t timer_data_id, struct
> rte_timer *tim)  }
> 
>  /* loop until rte_timer_stop() succeed */ -void
> +int
>  rte_timer_stop_sync(struct rte_timer *tim)  {
> +	struct rte_timer_data *timer_data;
> +	unsigned int lcore_id = rte_lcore_id();
> +
> +	TIMER_DATA_VALID_GET_OR_ERR_RET(default_data_id,
> timer_data, -EINVAL);
> +
> +	if (tim->status.state == RTE_TIMER_RUNNING &&
> +	(tim->status.owner != (uint16_t)lcore_id ||
> +	tim != timer_data->priv_timer[lcore_id].running_tim))
> +		return -1;
> +
>  	while (rte_timer_stop(tim) != 0)
>  		rte_pause();
> +
> +	return 0;
>  }
> 
>  /* Test the PENDING status of the timer handle tim */ diff --git
> a/lib/librte_timer/rte_timer.h b/lib/librte_timer/rte_timer.h index
> c6b3d450d..392ca423d 100644
> --- a/lib/librte_timer/rte_timer.h
> +++ b/lib/librte_timer/rte_timer.h
> @@ -275,7 +275,7 @@ int rte_timer_reset(struct rte_timer *tim, uint64_t
> ticks,
>   * @param arg
>   *   The user argument of the callback function.
>   */
> -void
> +int
>  rte_timer_reset_sync(struct rte_timer *tim, uint64_t ticks,
>  		     enum rte_timer_type type, unsigned tim_lcore,
>  		     rte_timer_cb_t fct, void *arg);
> @@ -314,7 +314,7 @@ int rte_timer_stop(struct rte_timer *tim);
>   * @param tim
>   *   The timer handle.
>   */
> -void rte_timer_stop_sync(struct rte_timer *tim);
> +int rte_timer_stop_sync(struct rte_timer *tim);
> 
>  /**
>   * Test if a timer is pending.
> --
> 2.17.1


^ permalink raw reply	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2020-07-28 19:04 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-07  9:03 [dpdk-dev] [PATCH] lib/librte_timer:fix corruption with reset Sarosh Arif
2020-07-07 16:09 ` Stephen Hemminger
2020-07-08  5:06 ` [dpdk-dev] [PATCH v2] " Sarosh Arif
2020-07-08 15:07   ` Stephen Hemminger
2020-07-09  7:05     ` Sarosh Arif
2020-07-08 15:08   ` Stephen Hemminger
2020-07-09  7:02     ` Sarosh Arif
2020-07-10  6:59 ` [dpdk-dev] [PATCH v3] " Sarosh Arif
2020-07-10 15:19   ` Stephen Hemminger
2020-07-28 19:04   ` Carrillo, Erik G

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