[dpdk-dev] [PATCH] eal/service: fix exit by resetting service lcores

[David Marchand]

On Tue, Mar 10, 2020 at 2:32 PM Harry van Haaren
<harry.van.haaren at intel.com> wrote:
>
> This commit releases all service cores from thier role,
> returning them to ROLE_RTE on rte_service_finalize().
>
> This may fix an issue relating to the service cores causing
> a race-condition on eal_cleanup(), where the service core
> could still be executing while the main thread has already
> free-d the service memory, leading to a segfault.

Adding rte_service_lcore_reset_all() just tells a (remaining) service
lcore to quit its loop, but does not close the race on lcore_states.

The backtrace shows the same.

(gdb) bt full
#0  rte_service_runner_func (arg=<optimized out>) at
../lib/librte_eal/common/rte_service.c:455
        service_mask = 1
        i = <optimized out>
        lcore = 1
        cs = 0x1003ea200
#1  0x00007ffff72030ef in eal_thread_loop (arg=<optimized out>) at
../lib/librte_eal/linux/eal/eal_thread.c:153
        fct_arg = <optimized out>
        c = 0 '\000'
        n = <optimized out>
        ret = <optimized out>
        lcore_id = <optimized out>
        thread_id = 140737203603200
        m2s = 14
        s2m = 22
        cpuset = "1", '\000' <repeats 175 times>,
"\200\000\000\000\000\000\000\000\221\354e\360\377\177", '\000'
<repeats 65 times>
        __func__ = "eal_thread_loop"
#2  0x00007ffff065ddd5 in start_thread () from /lib64/libpthread.so.0
No symbol table info available.
#3  0x00007ffff038702d in clone () from /lib64/libc.so.6
No symbol table info available.


I added a rte_eal_mp_wait_lcore(), to ensure that each service lcore
_did_ quit its loop.
@@ -123,6 +123,7 @@ rte_service_finalize(void)
                return;

        rte_service_lcore_reset_all();
+       rte_eal_mp_wait_lcore();

        rte_free(rte_services);
        rte_free(lcore_states);


I can't reproduce with this.

--
David Marchand