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| author | Martin KaFai Lau <kafai@fb.com> | 2015-08-14 11:05:53 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-08-17 14:28:03 -0700 |
| commit | a73e4195636c17f310b8530643a576f42b82385f (patch) | |
| tree | 084823d7d514bc015523526b8317ae05db15e629 /net/ipv6 | |
| parent | ad706862890171e02df1d7391b05599fb676ec18 (diff) | |
| download | linux-a73e4195636c17f310b8530643a576f42b82385f.tar.gz linux-a73e4195636c17f310b8530643a576f42b82385f.tar.bz2 linux-a73e4195636c17f310b8530643a576f42b82385f.zip | |
ipv6: Add rt6_make_pcpu_route()
It is a prep work for fixing a potential deadlock when creating
a pcpu rt.
The current rt6_get_pcpu_route() will also create a pcpu rt if one does not
exist. This patch moves the pcpu rt creation logic into another function,
rt6_make_pcpu_route().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
CC: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/route.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index c95c3197c186..0a82653efc88 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -993,13 +993,21 @@ static struct rt6_info *ip6_rt_pcpu_alloc(struct rt6_info *rt) /* It should be called with read_lock_bh(&tb6_lock) acquired */ static struct rt6_info *rt6_get_pcpu_route(struct rt6_info *rt) { - struct rt6_info *pcpu_rt, *prev, **p; + struct rt6_info *pcpu_rt, **p; p = this_cpu_ptr(rt->rt6i_pcpu); pcpu_rt = *p; - if (pcpu_rt) - goto done; + if (pcpu_rt) { + dst_hold(&pcpu_rt->dst); + rt6_dst_from_metrics_check(pcpu_rt); + } + return pcpu_rt; +} + +static struct rt6_info *rt6_make_pcpu_route(struct rt6_info *rt) +{ + struct rt6_info *pcpu_rt, *prev, **p; pcpu_rt = ip6_rt_pcpu_alloc(rt); if (!pcpu_rt) { @@ -1009,6 +1017,7 @@ static struct rt6_info *rt6_get_pcpu_route(struct rt6_info *rt) goto done; } + p = this_cpu_ptr(rt->rt6i_pcpu); prev = cmpxchg(p, NULL, pcpu_rt); if (prev) { /* If someone did it before us, return prev instead */ @@ -1093,8 +1102,11 @@ redo_rt6_select: rt->dst.lastuse = jiffies; rt->dst.__use++; pcpu_rt = rt6_get_pcpu_route(rt); - read_unlock_bh(&table->tb6_lock); + if (!pcpu_rt) + pcpu_rt = rt6_make_pcpu_route(rt); + + read_unlock_bh(&table->tb6_lock); return pcpu_rt; } } |