From a79af59efd20990473d579b1d8d70bb120f0920c Mon Sep 17 00:00:00 2001 From: Frank Filz Date: Tue, 27 Sep 2005 15:23:38 -0700 Subject: [NET]: Fix module reference counts for loadable protocol modules I have been experimenting with loadable protocol modules, and ran into several issues with module reference counting. The first issue was that __module_get failed at the BUG_ON check at the top of the routine (checking that my module reference count was not zero) when I created the first socket. When sk_alloc() is called, my module reference count was still 0. When I looked at why sctp didn't have this problem, I discovered that sctp creates a control socket during module init (when the module ref count is not 0), which keeps the reference count non-zero. This section has been updated to address the point Stephen raised about checking the return value of try_module_get(). The next problem arose when my socket init routine returned an error. This resulted in my module reference count being decremented below 0. My socket ops->release routine was also being called. The issue here is that sock_release() calls the ops->release routine and decrements the ref count if sock->ops is not NULL. Since the socket probably didn't get correctly initialized, this should not be done, so we will set sock->ops to NULL because we will not call try_module_get(). While searching for another bug, I also noticed that sys_accept() has a possibility of doing a module_put() when it did not do an __module_get so I re-ordered the call to security_socket_accept(). Signed-off-by: Frank Filz Signed-off-by: David S. Miller --- net/core/sock.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) (limited to 'net/core/sock.c') diff --git a/net/core/sock.c b/net/core/sock.c index ac63b56..928d2a1 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -660,16 +660,20 @@ struct sock *sk_alloc(int family, unsigned int __nocast priority, sock_lock_init(sk); } - if (security_sk_alloc(sk, family, priority)) { - if (slab != NULL) - kmem_cache_free(slab, sk); - else - kfree(sk); - sk = NULL; - } else - __module_get(prot->owner); + if (security_sk_alloc(sk, family, priority)) + goto out_free; + + if (!try_module_get(prot->owner)) + goto out_free; } return sk; + +out_free: + if (slab != NULL) + kmem_cache_free(slab, sk); + else + kfree(sk); + return NULL; } void sk_free(struct sock *sk) -- cgit v1.1 From dd0fc66fb33cd610bc1a5db8a5e232d34879b4d7 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 7 Oct 2005 07:46:04 +0100 Subject: [PATCH] gfp flags annotations - part 1 - added typedef unsigned int __nocast gfp_t; - replaced __nocast uses for gfp flags with gfp_t - it gives exactly the same warnings as far as sparse is concerned, doesn't change generated code (from gcc point of view we replaced unsigned int with typedef) and documents what's going on far better. Signed-off-by: Al Viro Signed-off-by: Linus Torvalds --- net/core/sock.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'net/core/sock.c') diff --git a/net/core/sock.c b/net/core/sock.c index 928d2a1..1c52fe8 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -637,7 +637,7 @@ lenout: * @prot: struct proto associated with this new sock instance * @zero_it: if we should zero the newly allocated sock */ -struct sock *sk_alloc(int family, unsigned int __nocast priority, +struct sock *sk_alloc(int family, gfp_t priority, struct proto *prot, int zero_it) { struct sock *sk = NULL; @@ -704,7 +704,7 @@ void sk_free(struct sock *sk) module_put(owner); } -struct sock *sk_clone(const struct sock *sk, const unsigned int __nocast priority) +struct sock *sk_clone(const struct sock *sk, const gfp_t priority) { struct sock *newsk = sk_alloc(sk->sk_family, priority, sk->sk_prot, 0); @@ -845,7 +845,7 @@ unsigned long sock_i_ino(struct sock *sk) * Allocate a skb from the socket's send buffer. */ struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force, - unsigned int __nocast priority) + gfp_t priority) { if (force || atomic_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf) { struct sk_buff * skb = alloc_skb(size, priority); @@ -861,7 +861,7 @@ struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force, * Allocate a skb from the socket's receive buffer. */ struct sk_buff *sock_rmalloc(struct sock *sk, unsigned long size, int force, - unsigned int __nocast priority) + gfp_t priority) { if (force || atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf) { struct sk_buff *skb = alloc_skb(size, priority); @@ -876,7 +876,7 @@ struct sk_buff *sock_rmalloc(struct sock *sk, unsigned long size, int force, /* * Allocate a memory block from the socket's option memory buffer. */ -void *sock_kmalloc(struct sock *sk, int size, unsigned int __nocast priority) +void *sock_kmalloc(struct sock *sk, int size, gfp_t priority) { if ((unsigned)size <= sysctl_optmem_max && atomic_read(&sk->sk_omem_alloc) + size < sysctl_optmem_max) { -- cgit v1.1