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authorMathias Krause <minipli@googlemail.com>2017-09-08 20:57:11 +0200
committerHerbert Xu <herbert@gondor.apana.org.au>2017-10-07 12:10:32 +0800
commit350ef88e7e922354f82a931897ad4a4ce6c686ff (patch)
tree1a4e182954c15959d059660ba124117c172fe5a3 /kernel/padata.c
parentcf5868c8a22dc2854b96e9569064bb92365549ca (diff)
downloadlinux-350ef88e7e922354f82a931897ad4a4ce6c686ff.tar.bz2
padata: ensure padata_do_serial() runs on the correct CPU
If the algorithm we're parallelizing is asynchronous we might change CPUs between padata_do_parallel() and padata_do_serial(). However, we don't expect this to happen as we need to enqueue the padata object into the per-cpu reorder queue we took it from, i.e. the same-cpu's parallel queue. Ensure we're not switching CPUs for a given padata object by tracking the CPU within the padata object. If the serial callback gets called on the wrong CPU, defer invoking padata_reorder() via a kernel worker on the CPU we're expected to run on. Signed-off-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'kernel/padata.c')
-rw-r--r--kernel/padata.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/kernel/padata.c b/kernel/padata.c
index b4066147bce4..f262c9a4e70a 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -131,6 +131,7 @@ int padata_do_parallel(struct padata_instance *pinst,
padata->cb_cpu = cb_cpu;
target_cpu = padata_cpu_hash(pd);
+ padata->cpu = target_cpu;
queue = per_cpu_ptr(pd->pqueue, target_cpu);
spin_lock(&queue->parallel.lock);
@@ -363,10 +364,21 @@ void padata_do_serial(struct padata_priv *padata)
int cpu;
struct padata_parallel_queue *pqueue;
struct parallel_data *pd;
+ int reorder_via_wq = 0;
pd = padata->pd;
cpu = get_cpu();
+
+ /* We need to run on the same CPU padata_do_parallel(.., padata, ..)
+ * was called on -- or, at least, enqueue the padata object into the
+ * correct per-cpu queue.
+ */
+ if (cpu != padata->cpu) {
+ reorder_via_wq = 1;
+ cpu = padata->cpu;
+ }
+
pqueue = per_cpu_ptr(pd->pqueue, cpu);
spin_lock(&pqueue->reorder.lock);
@@ -376,7 +388,13 @@ void padata_do_serial(struct padata_priv *padata)
put_cpu();
- padata_reorder(pd);
+ /* If we're running on the wrong CPU, call padata_reorder() via a
+ * kernel worker.
+ */
+ if (reorder_via_wq)
+ queue_work_on(cpu, pd->pinst->wq, &pqueue->reorder_work);
+ else
+ padata_reorder(pd);
}
EXPORT_SYMBOL(padata_do_serial);