Already sent this to several lists, but forgot netdev ;-)...
This one's sort of outside my normal area of expertise so sending this
as an RFC to gather feedback on the idea.
Some background:
The cifs_mount() and cifs_umount() functions currently send a signal to
the cifsd kthread prior to calling kthread_stop on it. The reasoning is
apparently that it's likely that cifsd will have called kernel_recvmsg()
and if it doesn't do this there can be a rather long delay when a
filesystem is unmounted.
The following patch is a first stab at removing this need. It makes it
so that in tcp_recvmsg() we also check kthread_should_stop() at any
point where we currently check to see if the task was signalled. If
that returns true, then it acts as if it were signalled.
I've tested this on a fairly recent kernel with a cifs module that
doesn't send signals on unmount and it seems to work as expected. I'm
just not clear on whether it will have any adverse side-effects.
Obviously if this approach is OK then we'll probably also want to fix
up other recvmsg functions (udp_recvmsg, etc).
Anyone care to comment?
Thanks,
Signed-off-by: Jeff Layton <[EMAIL PROTECTED]>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index bd4c295..1ad91fa 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -258,6 +258,7 @@
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/crypto.h>
+#include <linux/kthread.h>
#include <net/icmp.h>
#include <net/tcp.h>
@@ -1154,7 +1155,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg,
if (tp->urg_data && tp->urg_seq == *seq) {
if (copied)
break;
- if (signal_pending(current)) {
+ if (signal_pending(current) || kthread_should_stop()) {
copied = timeo ? sock_intr_errno(timeo) :
-EAGAIN;
break;
}
@@ -1197,6 +1198,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg,
(sk->sk_shutdown & RCV_SHUTDOWN) ||
!timeo ||
signal_pending(current) ||
+ kthread_should_stop() ||
(flags & MSG_PEEK))
break;
} else {
@@ -1227,7 +1229,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg,
break;
}
- if (signal_pending(current)) {
+ if (signal_pending(current) || kthread_should_stop()) {
copied = sock_intr_errno(timeo);
break;
}
-
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