Re: [PATCH v2] net: fix sleeping while atomic problem in sock mem_cgroup.

Eric Dumazet
2011-12-16T09:31:18Z

Le vendredi 16 décembre 2011 à 13:09 +0400, Glauber Costa a écrit :
> Since we can't scan the proto_list to initialize sock cgroups, as it
> holds a rwlock, and we also want to keep the code generic enough to
> avoid calling the initialization functions of protocols directly,
> I propose we keep the interested parties in a separate list. This list
> is protected by a mutex so we can sleep and do the necessary allocations.
>
> Also fixes a reference problem found by Randy Dunlap's randconfig.
>
> Signed-off-by: Glauber Costa <glommer@parallels.com>
> CC: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
> CC: David S. Miller <davem@davemloft.net>
> CC: Eric Dumazet <eric.dumazet@gmail.com>
> CC: Stephen Rothwell <sfr@canb.auug.org.au>
> CC: Randy Dunlap <rdunlap@xenotime.net>
> ---

Sorry to come late, but why dont we convert proto_list_lock to a mutex ?

net/core/sock.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 5a6a906..0c67fac 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -136,7 +136,7 @@
#include <net/tcp.h>
#endif

-static DEFINE_RWLOCK(proto_list_lock);
+static DEFINE_MUTEX(proto_list_mutex);
static LIST_HEAD(proto_list);

#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
@@ -145,7 +145,7 @@ int mem_cgroup_sockets_init(struct cgroup *cgrp, struct cgroup_subsys *ss)
struct proto *proto;
int ret = 0;

- read_lock(&proto_list_lock);
+ mutex_lock(&proto_list_mutex);
list_for_each_entry(proto, &proto_list, node) {
if (proto->init_cgroup) {
ret = proto->init_cgroup(cgrp, ss);
@@ -154,13 +154,13 @@ int mem_cgroup_sockets_init(struct cgroup *cgrp, struct cgroup_subsys *ss)
}
}

- read_unlock(&proto_list_lock);
+ mutex_unlock(&proto_list_mutex);
return ret;
out:
list_for_each_entry_continue_reverse(proto, &proto_list, node)
if (proto->destroy_cgroup)
proto->destroy_cgroup(cgrp, ss);
- read_unlock(&proto_list_lock);
+ mutex_unlock(&proto_list_mutex);
return ret;
}

@@ -168,11 +168,11 @@ void mem_cgroup_sockets_destroy(struct cgroup *cgrp, struct cgroup_subsys *ss)
{
struct proto *proto;

- read_lock(&proto_list_lock);
+ mutex_lock(&proto_list_mutex);
list_for_each_entry_reverse(proto, &proto_list, node)
if (proto->destroy_cgroup)
proto->destroy_cgroup(cgrp, ss);
- read_unlock(&proto_list_lock);
+ mutex_unlock(&proto_list_mutex);
}
#endif

@@ -2479,10 +2479,10 @@ int proto_register(struct proto *prot, int alloc_slab)
}
}

- write_lock(&proto_list_lock);
+ mutex_lock(&proto_list_mutex);
list_add(&prot->node, &proto_list);
assign_proto_idx(prot);
- write_unlock(&proto_list_lock);
+ mutex_unlock(&proto_list_mutex);
return 0;

out_free_timewait_sock_slab_name:
@@ -2505,10 +2505,10 @@ EXPORT_SYMBOL(proto_register);

void proto_unregister(struct proto *prot)
{
- write_lock(&proto_list_lock);
+ mutex_lock(&proto_list_mutex);
release_proto_idx(prot);
list_del(&prot->node);
- write_unlock(&proto_list_lock);
+ mutex_unlock(&proto_list_mutex);

if (prot->slab != NULL) {
kmem_cache_destroy(prot->slab);
@@ -2531,9 +2531,9 @@ EXPORT_SYMBOL(proto_unregister);

#ifdef CONFIG_PROC_FS
static void *proto_seq_start(struct seq_file *seq, loff_t *pos)
- __acquires(proto_list_lock)
+ __acquires(proto_list_mutex)
{
- read_lock(&proto_list_lock);
+ mutex_lock(&proto_list_mutex);
return seq_list_start_head(&proto_list, *pos);
}

@@ -2543,9 +2543,9 @@ static void *proto_seq_next(struct seq_file *seq, void *v, loff_t *pos)
}

static void proto_seq_stop(struct seq_file *seq, void *v)
- __releases(proto_list_lock)
+ __releases(proto_list_mutex)
{
- read_unlock(&proto_list_lock);
+ mutex_unlock(&proto_list_mutex);
}

static char proto_method_implemented(const void *method)