From: Stefan Hajnoczi <stefanha@redhat.com>
To: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org, Stefan Hajnoczi <stefanha@redhat.com>
Subject: [PATCH] device-dax: avoid hang on error before devm_memremap_pages()
Date: Tue, 31 Jul 2018 15:32:46 +0100 [thread overview]
Message-ID: <20180731143246.16915-1-stefanha@redhat.com> (raw)
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>
---
Found by code inspection. Compile-tested only.
---
drivers/dax/pmem.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index fd49b24fd6af..99e2aace8078 100644
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -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);
--
2.17.1
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
next reply other threads:[~2018-07-31 14:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-31 14:32 Stefan Hajnoczi [this message]
2018-08-01 0:26 ` [PATCH] device-dax: avoid hang on error before devm_memremap_pages() Dave Jiang
2018-09-11 6:02 ` Dan Williams
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180731143246.16915-1-stefanha@redhat.com \
--to=stefanha@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nvdimm@lists.01.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).