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service: fix early move to inactive status

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Assume thread T2 is a service lcore that is in the middle of executing
a service function.  Also, assume thread T1 concurrently calls
rte_service_lcore_stop(), which will set the "service_active_on_lcore"
state to false.  If thread T1 then calls rte_service_may_be_active(),
it can return zero even though T2 is still running the service function.
If T1 then proceeds to free data being used by T2, a crash can ensue.

Move the logic that clears the "service_active_on_lcore" state from the
rte_service_lcore_stop() function to the service_runner_func() to
ensure that we:
- don't let the "service_active_on_lcore" state linger as 1
- don't clear the state early

Fixes: 6550113be6 ("service: fix lingering active status")
Cc: stable@dpdk.org

Signed-off-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
Acked-by: Harry van Haaren <harry.van.haaren@intel.com>
This commit is contained in:
Erik Gabriel Carrillo 2022-10-20 14:00:41 -05:00 committed by David Marchand
parent 8a0cf0c455
commit 329280c53e
1 changed files with 7 additions and 6 deletions
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13
lib/eal/common/rte_service.c
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@ -479,6 +479,7 @@ static int32_t
service_runner_func(void *arg)
{
RTE_SET_USED(arg);
uint8_t i;
const int lcore = rte_lcore_id();
struct core_state *cs = &lcore_states[lcore];
@ -494,7 +495,6 @@ service_runner_func(void *arg)
const uint64_t service_mask = cs->service_mask;
uint8_t start_id;
uint8_t end_id;
uint8_t i;
if (service_mask == 0)
continue;
@ -510,6 +510,12 @@ service_runner_func(void *arg)
__atomic_store_n(&cs->loops, cs->loops + 1, __ATOMIC_RELAXED);
}
/* Switch off this core for all services, to ensure that future
* calls to may_be_active() know this core is switched off.
*/
for (i = 0; i < RTE_SERVICE_NUM_MAX; i++)
cs->service_active_on_lcore[i] = 0;
/* Use SEQ CST memory ordering to avoid any re-ordering around
* this store, ensuring that once this store is visible, the service
* lcore thread really is done in service cores code.
@ -806,11 +812,6 @@ rte_service_lcore_stop(uint32_t lcore)
__atomic_load_n(&rte_services[i].num_mapped_cores,
__ATOMIC_RELAXED));
/* Switch off this core for all services, to ensure that future
* calls to may_be_active() know this core is switched off.
*/
cs->service_active_on_lcore[i] = 0;
/* if the core is mapped, and the service is running, and this
* is the only core that is mapped, the service would cease to
* run if this core stopped, so fail instead.