From: Michael Ellerman mpe@ellerman.id.au
commit ad53db4acb415976761d7302f5b02e97f2bd097e upstream.
The recent commit 76d588dddc45 ("powerpc/imc-pmu: Fix use of mutex in IRQs disabled section") fixed warnings (and possible deadlocks) in the IMC PMU driver by converting the locking to use spinlocks.
It also converted the init-time nest_init_lock to a spinlock, even though it's not used at runtime in IRQ disabled sections or while holding other spinlocks.
This leads to warnings such as:
BUG: sleeping function called from invalid context at include/linux/percpu-rwsem.h:49 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper/0 preempt_count: 1, expected: 0 CPU: 7 PID: 1 Comm: swapper/0 Not tainted 6.2.0-rc2-14719-gf12cd06109f4-dirty #1 Hardware name: Mambo,Simulated-System POWER9 0x4e1203 opal:v6.6.6 PowerNV Call Trace: dump_stack_lvl+0x74/0xa8 (unreliable) __might_resched+0x178/0x1a0 __cpuhp_setup_state+0x64/0x1e0 init_imc_pmu+0xe48/0x1250 opal_imc_counters_probe+0x30c/0x6a0 platform_probe+0x78/0x110 really_probe+0x104/0x420 __driver_probe_device+0xb0/0x170 driver_probe_device+0x58/0x180 __driver_attach+0xd8/0x250 bus_for_each_dev+0xb4/0x140 driver_attach+0x34/0x50 bus_add_driver+0x1e8/0x2d0 driver_register+0xb4/0x1c0 __platform_driver_register+0x38/0x50 opal_imc_driver_init+0x2c/0x40 do_one_initcall+0x80/0x360 kernel_init_freeable+0x310/0x3b8 kernel_init+0x30/0x1a0 ret_from_kernel_thread+0x5c/0x64
Fix it by converting nest_init_lock back to a mutex, so that we can call sleeping functions while holding it. There is no interaction between nest_init_lock and the runtime spinlocks used by the actual PMU routines.
Fixes: 76d588dddc45 ("powerpc/imc-pmu: Fix use of mutex in IRQs disabled section") Tested-by: Kajol Jainkjain@linux.ibm.com Reviewed-by: Kajol Jainkjain@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20230130014401.540543-1-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/perf/imc-pmu.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
--- a/arch/powerpc/perf/imc-pmu.c +++ b/arch/powerpc/perf/imc-pmu.c @@ -21,7 +21,7 @@ * Used to avoid races in counting the nest-pmu units during hotplug * register and unregister */ -static DEFINE_SPINLOCK(nest_init_lock); +static DEFINE_MUTEX(nest_init_lock); static DEFINE_PER_CPU(struct imc_pmu_ref *, local_nest_imc_refc); static struct imc_pmu **per_nest_pmu_arr; static cpumask_t nest_imc_cpumask; @@ -1622,7 +1622,7 @@ static void imc_common_mem_free(struct i static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr) { if (pmu_ptr->domain == IMC_DOMAIN_NEST) { - spin_lock(&nest_init_lock); + mutex_lock(&nest_init_lock); if (nest_pmus == 1) { cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE); kfree(nest_imc_refc); @@ -1632,7 +1632,7 @@ static void imc_common_cpuhp_mem_free(st
if (nest_pmus > 0) nest_pmus--; - spin_unlock(&nest_init_lock); + mutex_unlock(&nest_init_lock); }
/* Free core_imc memory */ @@ -1789,11 +1789,11 @@ int init_imc_pmu(struct device_node *par * rest. To handle the cpuhotplug callback unregister, we track * the number of nest pmus in "nest_pmus". */ - spin_lock(&nest_init_lock); + mutex_lock(&nest_init_lock); if (nest_pmus == 0) { ret = init_nest_pmu_ref(); if (ret) { - spin_unlock(&nest_init_lock); + mutex_unlock(&nest_init_lock); kfree(per_nest_pmu_arr); per_nest_pmu_arr = NULL; goto err_free_mem; @@ -1801,7 +1801,7 @@ int init_imc_pmu(struct device_node *par /* Register for cpu hotplug notification. */ ret = nest_pmu_cpumask_init(); if (ret) { - spin_unlock(&nest_init_lock); + mutex_unlock(&nest_init_lock); kfree(nest_imc_refc); kfree(per_nest_pmu_arr); per_nest_pmu_arr = NULL; @@ -1809,7 +1809,7 @@ int init_imc_pmu(struct device_node *par } } nest_pmus++; - spin_unlock(&nest_init_lock); + mutex_unlock(&nest_init_lock); break; case IMC_DOMAIN_CORE: ret = core_imc_pmu_cpumask_init();