From: Benjamin Coddington <bcodding@redhat.com>
To: Trond Myklebust <trondmy@gmail.com>,
Anna Schumaker <Anna.Schumaker@netapp.com>
Cc: James Harvey <jamespharvey20@gmail.com>, linux-nfs@vger.kernel.org
Subject: [PATCH v2] SUNRPC: fix race to sk_err after xs_error_report
Date: Wed, 2 Oct 2019 07:03:56 -0400 [thread overview]
Message-ID: <d851f5c2e3aa2b1784a0cc7d42858781b6d07ab8.1570014121.git.bcodding@redhat.com> (raw)
Since commit 4f8943f80883 ("SUNRPC: Replace direct task wakeups from
softirq context") there has been a race to the value of the sk_err if both
XPRT_SOCK_WAKE_ERROR and XPRT_SOCK_WAKE_DISCONNECT are set. In that case,
we may end up losing the sk_err value that existed when xs_error_report was
called.
Fix this by reverting to the previous behavior: instead of using SO_ERROR
to retrieve the value at a later time (which might also return sk_err_soft),
copy the sk_err value onto struct sock_xprt, and use that value to wake
pending tasks.
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Fixes: 4f8943f80883 ("SUNRPC: Replace direct task wakeups from softirq context")
8<-----------------------------------------------------------------------------
Changes on V2:
- move xprt_err into a hole in struct sock_xprt
- add an memory barrier to ensure the error is visble to the
error_worker
---
include/linux/sunrpc/xprtsock.h | 1 +
net/sunrpc/xprtsock.c | 16 ++++++++--------
2 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/include/linux/sunrpc/xprtsock.h b/include/linux/sunrpc/xprtsock.h
index 7638dbe7bc50..a940de03808d 100644
--- a/include/linux/sunrpc/xprtsock.h
+++ b/include/linux/sunrpc/xprtsock.h
@@ -61,6 +61,7 @@ struct sock_xprt {
struct mutex recv_mutex;
struct sockaddr_storage srcaddr;
unsigned short srcport;
+ int xprt_err;
/*
* UDP socket buffer size parameters
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index e2176c167a57..25ff097d6e21 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1250,12 +1250,15 @@ static void xs_error_report(struct sock *sk)
goto out;
transport = container_of(xprt, struct sock_xprt, xprt);
- err = -sk->sk_err;
- if (err == 0)
+ transport->xprt_err = -sk->sk_err;
+ if (transport->xprt_err == 0)
goto out;
dprintk("RPC: xs_error_report client %p, error=%d...\n",
- xprt, -err);
- trace_rpc_socket_error(xprt, sk->sk_socket, err);
+ xprt, -transport->xprt_err);
+ trace_rpc_socket_error(xprt, sk->sk_socket, transport->xprt_err);
+
+ /* barrier ensures xprt_err is set before XPRT_SOCK_WAKE_ERROR */
+ smp_mb__before_atomic();
xs_run_error_worker(transport, XPRT_SOCK_WAKE_ERROR);
out:
read_unlock_bh(&sk->sk_callback_lock);
@@ -2470,7 +2473,6 @@ static void xs_wake_write(struct sock_xprt *transport)
static void xs_wake_error(struct sock_xprt *transport)
{
int sockerr;
- int sockerr_len = sizeof(sockerr);
if (!test_bit(XPRT_SOCK_WAKE_ERROR, &transport->sock_state))
return;
@@ -2479,9 +2481,7 @@ static void xs_wake_error(struct sock_xprt *transport)
goto out;
if (!test_and_clear_bit(XPRT_SOCK_WAKE_ERROR, &transport->sock_state))
goto out;
- if (kernel_getsockopt(transport->sock, SOL_SOCKET, SO_ERROR,
- (char *)&sockerr, &sockerr_len) != 0)
- goto out;
+ sockerr = xchg(&transport->xprt_err, 0);
if (sockerr < 0)
xprt_wake_pending_tasks(&transport->xprt, sockerr);
out:
--
2.20.1
next reply other threads:[~2019-10-02 11:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-02 11:03 Benjamin Coddington [this message]
2019-10-02 14:12 ` [PATCH v2] SUNRPC: fix race to sk_err after xs_error_report Schumaker, Anna
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=d851f5c2e3aa2b1784a0cc7d42858781b6d07ab8.1570014121.git.bcodding@redhat.com \
--to=bcodding@redhat.com \
--cc=Anna.Schumaker@netapp.com \
--cc=jamespharvey20@gmail.com \
--cc=linux-nfs@vger.kernel.org \
--cc=trondmy@gmail.com \
/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).