The conversion change the behaviour of how the hotplug hooks were invoked: Before one CPU at a time invoked them all. Now on registration each hook is invoked by all CPUs (one after the other) before the next state is invoked. In amd_uncore_cpu_up_prepare() we allocate an uncore struct for each CPU with id 0. In amd_uncore_cpu_starting() we set the ID and search of others to replace it if available. CPU0 finds another struct with id 0 and puts its on the kill list. CPU1 find the struct of CPU0 and puts its on the kill list. The online event will free them. To fix this I use an id of -1 assuming that no uncore with such an id will show up. Step two is use a list to free the not needed elements.
Reported-by: Eric Sandeen <[email protected]> Tested-by: Eric Sandeen <[email protected]> Fixes: 96b2bd3866a0 ("perf/x86/amd/uncore: Convert to hotplug state machine") Signed-off-by: Sebastian Andrzej Siewior <[email protected]> --- arch/x86/events/amd/uncore.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c index e6131d4454e6..65577f081d07 100644 --- a/arch/x86/events/amd/uncore.c +++ b/arch/x86/events/amd/uncore.c @@ -29,6 +29,8 @@ #define COUNTER_SHIFT 16 +static HLIST_HEAD(uncore_unused_list); + struct amd_uncore { int id; int refcnt; @@ -39,7 +41,7 @@ struct amd_uncore { cpumask_t *active_mask; struct pmu *pmu; struct perf_event *events[MAX_COUNTERS]; - struct amd_uncore *free_when_cpu_online; + struct hlist_node node; }; static struct amd_uncore * __percpu *amd_uncore_nb; @@ -306,6 +308,7 @@ static int amd_uncore_cpu_up_prepare(unsigned int cpu) uncore_nb->msr_base = MSR_F15H_NB_PERF_CTL; uncore_nb->active_mask = &amd_nb_active_mask; uncore_nb->pmu = &amd_nb_pmu; + uncore_nb->id = -1; *per_cpu_ptr(amd_uncore_nb, cpu) = uncore_nb; } @@ -319,6 +322,7 @@ static int amd_uncore_cpu_up_prepare(unsigned int cpu) uncore_l2->msr_base = MSR_F16H_L2I_PERF_CTL; uncore_l2->active_mask = &amd_l2_active_mask; uncore_l2->pmu = &amd_l2_pmu; + uncore_l2->id = -1; *per_cpu_ptr(amd_uncore_l2, cpu) = uncore_l2; } @@ -348,7 +352,7 @@ amd_uncore_find_online_sibling(struct amd_uncore *this, continue; if (this->id == that->id) { - that->free_when_cpu_online = this; + hlist_add_head(&this->node, &uncore_unused_list); this = that; break; } @@ -388,13 +392,23 @@ static int amd_uncore_cpu_starting(unsigned int cpu) return 0; } +static void uncore_clean_online(void) +{ + struct amd_uncore *uncore; + struct hlist_node *n; + + hlist_for_each_entry_safe(uncore, n, &uncore_unused_list, node) { + hlist_del(&uncore->node); + kfree(uncore); + } +} + static void uncore_online(unsigned int cpu, struct amd_uncore * __percpu *uncores) { struct amd_uncore *uncore = *per_cpu_ptr(uncores, cpu); - kfree(uncore->free_when_cpu_online); - uncore->free_when_cpu_online = NULL; + uncore_clean_online(); if (cpu == uncore->cpu) cpumask_set_cpu(cpu, uncore->active_mask); -- 2.9.3
