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From: Arnd Bergmann <arnd@arndb.de>
To: Andrew Hendry <andrew.hendry@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-x25@vger.kernel.org,
	netdev@vger.kernel.org
Subject: [PATCH v2] x25: remove the BKL
Date: Thu, 27 Jan 2011 13:38:38 +0100	[thread overview]
Message-ID: <201101271338.39295.arnd@arndb.de> (raw)
In-Reply-To: <201101271317.01502.arnd@arndb.de>

This replaces all instances of lock_kernel in x25
with lock_sock, taking care to release the socket
lock around sleeping functions (sock_alloc_send_skb
and skb_recv_datagram). It is not clear whether
this is a correct solution, but it seem to be what
other protocols do in the same situation.

Compile-tested only.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Hendry <andrew.hendry@gmail.com>
Cc: linux-x25@vger.kernel.org
Cc: netdev@vger.kernel.org
---
v2: fix possible NULL-pointer dereference in x25_sendmsg

 net/x25/Kconfig   |    1 -
 net/x25/af_x25.c  |   58 ++++++++++++++++------------------------------------
 net/x25/x25_out.c |    7 ++++-
 3 files changed, 23 insertions(+), 43 deletions(-)

diff --git a/net/x25/Kconfig b/net/x25/Kconfig
index 2196e55..e6759c9 100644
--- a/net/x25/Kconfig
+++ b/net/x25/Kconfig
@@ -5,7 +5,6 @@
 config X25
 	tristate "CCITT X.25 Packet Layer (EXPERIMENTAL)"
 	depends on EXPERIMENTAL
-	depends on BKL # should be fixable
 	---help---
 	  X.25 is a set of standardized network protocols, similar in scope to
 	  frame relay; the one physical line from your box to the X.25 network
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index ad96ee9..4680b1e 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -40,7 +40,6 @@
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
-#include <linux/smp_lock.h>
 #include <linux/timer.h>
 #include <linux/string.h>
 #include <linux/net.h>
@@ -432,15 +431,6 @@ void x25_destroy_socket_from_timer(struct sock *sk)
 	sock_put(sk);
 }
 
-static void x25_destroy_socket(struct sock *sk)
-{
-	sock_hold(sk);
-	lock_sock(sk);
-	__x25_destroy_socket(sk);
-	release_sock(sk);
-	sock_put(sk);
-}
-
 /*
  *	Handling for system calls applied via the various interfaces to a
  *	X.25 socket object.
@@ -647,18 +637,19 @@ static int x25_release(struct socket *sock)
 	struct sock *sk = sock->sk;
 	struct x25_sock *x25;
 
-	lock_kernel();
 	if (!sk)
-		goto out;
+		return 0;
 
 	x25 = x25_sk(sk);
 
+	sock_hold(sk);
+	lock_sock(sk);
 	switch (x25->state) {
 
 		case X25_STATE_0:
 		case X25_STATE_2:
 			x25_disconnect(sk, 0, 0, 0);
-			x25_destroy_socket(sk);
+			__x25_destroy_socket(sk);
 			goto out;
 
 		case X25_STATE_1:
@@ -678,7 +669,8 @@ static int x25_release(struct socket *sock)
 
 	sock_orphan(sk);
 out:
-	unlock_kernel();
+	release_sock(sk);
+	sock_put(sk);
 	return 0;
 }
 
@@ -1085,7 +1077,7 @@ static int x25_sendmsg(struct kiocb *iocb, struct socket *sock,
 	size_t size;
 	int qbit = 0, rc = -EINVAL;
 
-	lock_kernel();
+	lock_sock(sk);
 	if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_OOB|MSG_EOR|MSG_CMSG_COMPAT))
 		goto out;
 
@@ -1148,7 +1140,9 @@ static int x25_sendmsg(struct kiocb *iocb, struct socket *sock,
 
 	size = len + X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
 
+	release_sock(sk);
 	skb = sock_alloc_send_skb(sk, size, noblock, &rc);
+	lock_sock(sk);
 	if (!skb)
 		goto out;
 	X25_SKB_CB(skb)->flags = msg->msg_flags;
@@ -1231,26 +1225,10 @@ static int x25_sendmsg(struct kiocb *iocb, struct socket *sock,
 			len++;
 	}
 
-	/*
-	 * lock_sock() is currently only used to serialize this x25_kick()
-	 * against input-driven x25_kick() calls. It currently only blocks
-	 * incoming packets for this socket and does not protect against
-	 * any other socket state changes and is not called from anywhere
-	 * else. As x25_kick() cannot block and as long as all socket
-	 * operations are BKL-wrapped, we don't need take to care about
-	 * purging the backlog queue in x25_release().
-	 *
-	 * Using lock_sock() to protect all socket operations entirely
-	 * (and making the whole x25 stack SMP aware) unfortunately would
-	 * require major changes to {send,recv}msg and skb allocation methods.
-	 * -> 2.5 ;)
-	 */
-	lock_sock(sk);
 	x25_kick(sk);
-	release_sock(sk);
 	rc = len;
 out:
-	unlock_kernel();
+	release_sock(sk);
 	return rc;
 out_kfree_skb:
 	kfree_skb(skb);
@@ -1271,7 +1249,7 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock,
 	unsigned char *asmptr;
 	int rc = -ENOTCONN;
 
-	lock_kernel();
+	lock_sock(sk);
 	/*
 	 * This works for seqpacket too. The receiver has ordered the queue for
 	 * us! We do one quick check first though
@@ -1300,8 +1278,10 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock,
 		msg->msg_flags |= MSG_OOB;
 	} else {
 		/* Now we can treat all alike */
+		release_sock(sk);
 		skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT,
 					flags & MSG_DONTWAIT, &rc);
+		lock_sock(sk);
 		if (!skb)
 			goto out;
 
@@ -1338,14 +1318,12 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock,
 
 	msg->msg_namelen = sizeof(struct sockaddr_x25);
 
-	lock_sock(sk);
 	x25_check_rbuf(sk);
-	release_sock(sk);
 	rc = copied;
 out_free_dgram:
 	skb_free_datagram(sk, skb);
 out:
-	unlock_kernel();
+	release_sock(sk);
 	return rc;
 }
 
@@ -1581,18 +1559,18 @@ out_cud_release:
 
 		case SIOCX25CALLACCPTAPPRV: {
 			rc = -EINVAL;
-			lock_kernel();
+			lock_sock(sk);
 			if (sk->sk_state != TCP_CLOSE)
 				break;
 			clear_bit(X25_ACCPT_APPRV_FLAG, &x25->flags);
-			unlock_kernel();
+			release_sock(sk);
 			rc = 0;
 			break;
 		}
 
 		case SIOCX25SENDCALLACCPT:  {
 			rc = -EINVAL;
-			lock_kernel();
+			lock_sock(sk);
 			if (sk->sk_state != TCP_ESTABLISHED)
 				break;
 			/* must call accptapprv above */
@@ -1600,7 +1578,7 @@ out_cud_release:
 				break;
 			x25_write_internal(sk, X25_CALL_ACCEPTED);
 			x25->state = X25_STATE_3;
-			unlock_kernel();
+			release_sock(sk);
 			rc = 0;
 			break;
 		}
diff --git a/net/x25/x25_out.c b/net/x25/x25_out.c
index d00649f..f1a6ff1 100644
--- a/net/x25/x25_out.c
+++ b/net/x25/x25_out.c
@@ -68,8 +68,11 @@ int x25_output(struct sock *sk, struct sk_buff *skb)
 		frontlen = skb_headroom(skb);
 
 		while (skb->len > 0) {
-			if ((skbn = sock_alloc_send_skb(sk, frontlen + max_len,
-							noblock, &err)) == NULL){
+			release_sock(sk);
+			skbn = sock_alloc_send_skb(sk, frontlen + max_len,
+						   1, &err);
+			lock_sock(sk);
+			if (!skbn) {
 				if (err == -EWOULDBLOCK && noblock){
 					kfree_skb(skb);
 					return sent;

  reply	other threads:[~2011-01-27 12:38 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-25 22:17 [RFC 00/20] Proposal for remaining BKL users Arnd Bergmann
2011-01-25 22:17 ` Arnd Bergmann
2011-01-25 22:17 ` [PATCH 01/20] drm/i810: remove the BKL Arnd Bergmann
2011-01-25 22:17 ` [PATCH 02/20] drm: remove i830 driver Arnd Bergmann
2011-01-25 22:17 ` [PATCH 03/20] staging/usbip: convert to kthread Arnd Bergmann
2011-01-28 17:53   ` Max Vozeler
2011-01-28 18:48     ` Arnd Bergmann
2011-03-01 22:15     ` Arnd Bergmann
2011-01-25 22:17 ` [PATCH 04/20] staging/cx25721: serialize access to devlist Arnd Bergmann
2011-01-26 16:23   ` Palash Bandyopadhyay
2011-01-31 21:37   ` Greg KH
2011-01-25 22:17 ` [PATCH 05/20] staging/go7007: remove the BKL Arnd Bergmann
2011-01-25 22:17 ` [PATCH 06/20] staging: Remove autofs3 Arnd Bergmann
2011-01-26  7:41   ` H. Peter Anvin
2011-01-25 22:17 ` [PATCH 07/20] staging: remove smbfs Arnd Bergmann
2011-01-25 22:17 ` [PATCH 08/20] adfs: remove the big kernel lock Arnd Bergmann
2011-01-25 22:20   ` Russell King
2011-01-25 22:17 ` [PATCH 09/20] hpfs: rename big kernel lock to hpfs_lock Arnd Bergmann
2011-01-25 22:17 ` [PATCH 10/20] hpfs: replace BKL with a global mutex Arnd Bergmann
2011-01-26  0:15   ` Andi Kleen
2011-01-26  0:19   ` Andi Kleen
2011-01-26 12:48     ` [PATCH v2] hpfs: remove the BKL Arnd Bergmann
2011-01-26 12:50     ` [PATCH 10/20] hpfs: replace BKL with a global mutex Arnd Bergmann
2011-01-26 16:52       ` Andi Kleen
2011-01-27  5:01         ` Nick Piggin
2011-01-27 10:57           ` Miklos Szeredi
2011-01-25 22:17 ` [PATCH 11/20] hpfs: move to drivers/staging Arnd Bergmann
2011-02-07 16:17   ` Mikulas Patocka
2011-02-07 19:31     ` Arnd Bergmann
2011-01-25 22:17 ` [PATCH 12/20] x25: remove the BKL Arnd Bergmann
2011-01-27 10:07   ` Andrew Hendry
2011-01-27 12:17     ` Arnd Bergmann
2011-01-27 12:38       ` Arnd Bergmann [this message]
2011-01-27 13:20         ` [PATCH v2] " Eric Dumazet
2011-01-27 13:43           ` Arnd Bergmann
2011-01-25 22:17 ` [PATCH 13/20] appletalk: move to staging Arnd Bergmann
2011-01-25 22:17 ` [PATCH 14/20] staging/appletalk: remove the BKL Arnd Bergmann
2011-01-25 22:29   ` David Miller
2011-01-26 12:57     ` Arnd Bergmann
2011-01-25 22:17 ` [PATCH 15/20] ufs: " Arnd Bergmann
2011-01-26  2:30   ` Nick Bowler
2011-01-26 12:53     ` Arnd Bergmann
2011-01-27  5:47   ` Nick Piggin
2011-01-27 13:13     ` Arnd Bergmann
2011-01-25 22:17 ` [PATCH 16/20] ipx: " Arnd Bergmann
2011-01-25 22:17 ` [PATCH 17/20] tracing: don't trace " Arnd Bergmann
2011-01-25 22:28   ` Frederic Weisbecker
2011-01-25 22:17 ` [PATCH 18/20] rtmutex-tester: remove BKL tests Arnd Bergmann
2011-01-26 15:00   ` [tip:core/locking] rtmutex-tester: Remove " tip-bot for Arnd Bergmann
2011-02-22 20:57   ` [tip:irq/core] rtmutex: tester: " tip-bot for Arnd Bergmann
2011-01-25 22:17 ` [PATCH 19/20] drivers: remove extraneous includes of smp_lock.h Arnd Bergmann
2011-01-25 22:17 ` [PATCH 20/20] BKL: That's all, folks Arnd Bergmann
2011-01-26  6:19   ` Ingo Molnar
2011-01-26  8:47     ` Alan Cox
2011-01-26 11:01       ` Ingo Molnar
2011-01-26 11:22   ` Thomas Gleixner
2011-01-26  2:22 ` [RFC 00/20] Proposal for remaining BKL users Greg KH
2011-01-26  2:22   ` Greg KH
2011-01-26 11:31   ` Arnd Bergmann
2011-01-26 11:31     ` Arnd Bergmann
2011-01-26 11:58     ` Mauro Carvalho Chehab
2011-01-26 13:45       ` Arnd Bergmann
2011-01-26 13:45         ` Arnd Bergmann
2011-01-26 16:24         ` Palash Bandyopadhyay

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