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authorHerbert Xu <herbert@gondor.apana.org.au>2009-01-30 14:12:06 -0800
committerDavid S. Miller <davem@davemloft.net>2009-01-30 14:13:49 -0800
commit905db44087855e3c1709f538ecdc22fd149cadd8 (patch)
tree645708af472fd26bb73b5cd6abe10640322a3b93 /net
parent1974cc205e63cec4a17a6b3fca31fa4240ded77e (diff)
downloadlinux-2.6.38-lt-ux500-905db44087855e3c1709f538ecdc22fd149cadd8.tar.gz
packet: Avoid lock_sock in mmap handler
As the mmap handler gets called under mmap_sem, and we may grab mmap_sem elsewhere under the socket lock to access user data, we should avoid grabbing the socket lock in the mmap handler. Since the only thing we care about in the mmap handler is for pg_vec* to be invariant, i.e., to exclude packet_set_ring, we can achieve this by simply using a new mutex. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Martin MOKREJŠ <mmokrejs@ribosome.natur.cuni.cz> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/packet/af_packet.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5f94db2f3e9..9454d4ae46d 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -77,6 +77,7 @@
#include <linux/poll.h>
#include <linux/module.h>
#include <linux/init.h>
+#include <linux/mutex.h>
#ifdef CONFIG_INET
#include <net/inet_common.h>
@@ -175,6 +176,7 @@ struct packet_sock {
#endif
struct packet_type prot_hook;
spinlock_t bind_lock;
+ struct mutex pg_vec_lock;
unsigned int running:1, /* prot_hook is attached*/
auxdata:1,
origdev:1;
@@ -1069,6 +1071,7 @@ static int packet_create(struct net *net, struct socket *sock, int protocol)
*/
spin_lock_init(&po->bind_lock);
+ mutex_init(&po->pg_vec_lock);
po->prot_hook.func = packet_rcv;
if (sock->type == SOCK_PACKET)
@@ -1865,6 +1868,7 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
synchronize_net();
err = -EBUSY;
+ mutex_lock(&po->pg_vec_lock);
if (closing || atomic_read(&po->mapped) == 0) {
err = 0;
#define XC(a, b) ({ __typeof__ ((a)) __t; __t = (a); (a) = (b); __t; })
@@ -1886,6 +1890,7 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
if (atomic_read(&po->mapped))
printk(KERN_DEBUG "packet_mmap: vma is busy: %d\n", atomic_read(&po->mapped));
}
+ mutex_unlock(&po->pg_vec_lock);
spin_lock(&po->bind_lock);
if (was_running && !po->running) {
@@ -1918,7 +1923,7 @@ static int packet_mmap(struct file *file, struct socket *sock, struct vm_area_st
size = vma->vm_end - vma->vm_start;
- lock_sock(sk);
+ mutex_lock(&po->pg_vec_lock);
if (po->pg_vec == NULL)
goto out;
if (size != po->pg_vec_len*po->pg_vec_pages*PAGE_SIZE)
@@ -1941,7 +1946,7 @@ static int packet_mmap(struct file *file, struct socket *sock, struct vm_area_st
err = 0;
out:
- release_sock(sk);
+ mutex_unlock(&po->pg_vec_lock);
return err;
}
#endif