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device-dax: avoid hang on error before devm_memremap_pages() 

dax_pmem_percpu_exit() waits for dax_pmem_percpu_release() to invoke the
dax_pmem->cmp completion.  Unfortunately this approach to cleaning up
the percpu_ref only works after devm_memremap_pages() was successful.

If devm_add_action_or_reset() or devm_memremap_pages() fails,
dax_pmem_percpu_release() is not invoked.  Therefore
dax_pmem_percpu_exit() hangs waiting for the completion:

  rc = devm_add_action_or_reset(dev, dax_pmem_percpu_exit,
  				&dax_pmem->ref);
  if (rc)
  	return rc;

  dax_pmem->pgmap.ref = &dax_pmem->ref;
  addr = devm_memremap_pages(dev, &dax_pmem->pgmap);

Avoid the hang by calling percpu_ref_exit() in the error paths instead
of going through dax_pmem_percpu_exit().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Stefan Hajnoczi 2018-07-31 15:32:46 +01:00 committed by Dave Jiang
parent b4d4702f30
commit b7751410c1
1 changed files with 8 additions and 4 deletions
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12
drivers/dax/pmem.c
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@ -105,15 +105,19 @@ static int dax_pmem_probe(struct device *dev)
if (rc)
return rc;
rc = devm_add_action_or_reset(dev, dax_pmem_percpu_exit,
&dax_pmem->ref);
if (rc)
rc = devm_add_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref);
if (rc) {
percpu_ref_exit(&dax_pmem->ref);
return rc;
}
dax_pmem->pgmap.ref = &dax_pmem->ref;
addr = devm_memremap_pages(dev, &dax_pmem->pgmap);
if (IS_ERR(addr))
if (IS_ERR(addr)) {
devm_remove_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref);
percpu_ref_exit(&dax_pmem->ref);
return PTR_ERR(addr);
}
rc = devm_add_action_or_reset(dev, dax_pmem_percpu_kill,
&dax_pmem->ref);