Messages in this thread Patch in this message |  | | From | Tomáš Glozar <> | Subject | [PATCH] nd_btt: Make BTT lanes preemptible | Date | Tue, 12 Sep 2023 10:24:40 +0200 |
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From: Tomas Glozar <tglozar@redhat.com>
nd_region_acquire_lane uses get_cpu, which disables preemption. This is an issue on PREEMPT_RT kernels, since btt_write_pg and also nd_region_acquire_lane itself take a spin lock, resulting in BUG: sleeping function called from invalid context.
Fix the issue by replacing get_cpu with smp_process_id and migrate_disable when needed. This makes BTT operations preemptible, thus permitting the use of spin_lock.
Fixes: 5212e11fde4d ("nd_btt: atomic sector updates") Signed-off-by: Tomas Glozar <tglozar@redhat.com> --- drivers/nvdimm/region_devs.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index 0a81f87f6f6c..e2f1fb99707f 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -939,7 +939,8 @@ unsigned int nd_region_acquire_lane(struct nd_region *nd_region) { unsigned int cpu, lane; - cpu = get_cpu(); + migrate_disable(); + cpu = smp_processor_id(); if (nd_region->num_lanes < nr_cpu_ids) { struct nd_percpu_lane *ndl_lock, *ndl_count; @@ -958,16 +959,15 @@ EXPORT_SYMBOL(nd_region_acquire_lane); void nd_region_release_lane(struct nd_region *nd_region, unsigned int lane) { if (nd_region->num_lanes < nr_cpu_ids) { - unsigned int cpu = get_cpu(); + unsigned int cpu = smp_processor_id(); struct nd_percpu_lane *ndl_lock, *ndl_count; ndl_count = per_cpu_ptr(nd_region->lane, cpu); ndl_lock = per_cpu_ptr(nd_region->lane, lane); if (--ndl_count->count == 0) spin_unlock(&ndl_lock->lock); - put_cpu(); } - put_cpu(); + migrate_enable(); } EXPORT_SYMBOL(nd_region_release_lane); -- 2.39.3
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