linux-toradex.git/net/ipv4/inet_fragment.c, branch v4.9.85

Revert "net: use lib/percpu_counter API for fragmentation mem accounting"

2017-09-20T06:19:55+00:00

[ Upstream commit fb452a1aa3fd4034d7999e309c5466ff2d7005aa ]

This reverts commit 6d7b857d541ecd1d9bd997c97242d4ef94b19de2.

There is a bug in fragmentation codes use of the percpu_counter API,
that can cause issues on systems with many CPUs.

The frag_mem_limit() just reads the global counter (fbc->count),
without considering other CPUs can have upto batch size (130K) that
haven't been subtracted yet.  Due to the 3MBytes lower thresh limit,
this become dangerous at >=24 CPUs (3*1024*1024/130000=24).

The correct API usage would be to use __percpu_counter_compare() which
does the right thing, and takes into account the number of (online)
CPUs and batch size, to account for this and call __percpu_counter_sum()
when needed.

We choose to revert the use of the lib/percpu_counter API for frag
memory accounting for several reasons:

1) On systems with CPUs > 24, the heavier fully locked
   __percpu_counter_sum() is always invoked, which will be more
   expensive than the atomic_t that is reverted to.

Given systems with more than 24 CPUs are becoming common this doesn't
seem like a good option.  To mitigate this, the batch size could be
decreased and thresh be increased.

2) The add_frag_mem_limit+sub_frag_mem_limit pairs happen on the RX
   CPU, before SKBs are pushed into sockets on remote CPUs.  Given
   NICs can only hash on L2 part of the IP-header, the NIC-RXq's will
   likely be limited.  Thus, a fair chance that atomic add+dec happen
   on the same CPU.

Revert note that commit 1d6119baf061 ("net: fix percpu memory leaks")
removed init_frag_mem_limit() and instead use inet_frags_init_net().
After this revert, inet_frags_uninit_net() becomes empty.

Fixes: 6d7b857d541e ("net: use lib/percpu_counter API for fragmentation mem accounting")
Fixes: 1d6119baf061 ("net: fix percpu memory leaks")
Signed-off-by: Jesper Dangaard Brouer 
Acked-by: Florian Westphal 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: disable fragment reassembly if high_thresh is zero

2016-06-06T02:56:42+00:00

Before commit 6d7b857d541e ("net: use lib/percpu_counter API for
fragmentation mem accounting"), setting the reassembly high threshold
to 0 prevented fragment reassembly as first fragment would be always
evicted before second could be added to the queue. While inefficient,
some users apparently relied on this method.

Since the commit mentioned above, a percpu counter is used for
reassembly memory accounting and high batch size avoids taking slow path
in most common scenarios. As a result, a whole full sized packet can be
reassembled without the percpu counter's main counter changing its value
so that even with high_thresh set to 0, fragmented packets can be still
reassembled and processed.

Add explicit check preventing reassembly if high threshold is zero.

Signed-off-by: Michal Kubecek 
Signed-off-by: David S. Miller

inet: kill unused skb_free op

2016-01-06T03:25:57+00:00

The only user was removed in commit
029f7f3b8701cc7a ("netfilter: ipv6: nf_defrag: avoid/free clone operations").

Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

net: fix percpu memory leaks

2015-11-03T03:47:14+00:00

This patch fixes following problems :

1) percpu_counter_init() can return an error, therefore
  init_frag_mem_limit() must propagate this error so that
  inet_frags_init_net() can do the same up to its callers.

2) If ip[46]_frags_ns_ctl_register() fail, we must unwind
   properly and free the percpu_counter.

Without this fix, we leave freed object in percpu_counters
global list (if CONFIG_HOTPLUG_CPU) leading to crashes.

This bug was detected by KASAN and syzkaller tool
(http://github.com/google/syzkaller)

Fixes: 6d7b857d541e ("net: use lib/percpu_counter API for fragmentation mem accounting")
Signed-off-by: Eric Dumazet 
Reported-by: Dmitry Vyukov 
Cc: Hannes Frederic Sowa 
Cc: Jesper Dangaard Brouer 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller

inet: frags: remove INET_FRAG_EVICTED and use list_evictor for the test

2015-07-27T04:00:15+00:00

We can simply remove the INET_FRAG_EVICTED flag to avoid all the flags
race conditions with the evictor and use a participation test for the
evictor list, when we're at that point (after inet_frag_kill) in the
timer there're 2 possible cases:

1. The evictor added the entry to its evictor list while the timer was
waiting for the chainlock
or
2. The timer unchained the entry and the evictor won't see it

In both cases we should be able to see list_evictor correctly due
to the sync on the chainlock.

Joint work with Florian Westphal.

Tested-by: Frank Schreuder 
Signed-off-by: Nikolay Aleksandrov 
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

inet: frag: don't wait for timer deletion when evicting

2015-07-27T04:00:14+00:00

Frank reports 'NMI watchdog: BUG: soft lockup' errors when
load is high.  Instead of (potentially) unbounded restarts of the
eviction process, just skip to the next entry.

One caveat is that, when a netns is exiting, a timer may still be running
by the time inet_evict_bucket returns.

We use the frag memory accounting to wait for outstanding timers,
so that when we free the percpu counter we can be sure no running
timer will trip over it.

Reported-and-tested-by: Frank Schreuder 
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

inet: frag: change *_frag_mem_limit functions to take netns_frags as argument

2015-07-27T04:00:14+00:00

Followup patch will call it after inet_frag_queue was freed, so q->net
doesn't work anymore (but netf = q->net; free(q); mem_limit(netf) would).

Tested-by: Frank Schreuder 
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

inet: frag: don't re-use chainlist for evictor

2015-07-27T04:00:14+00:00

commit 65ba1f1ec0eff ("inet: frags: fix a race between inet_evict_bucket
and inet_frag_kill") describes the bug, but the fix doesn't work reliably.

Problem is that ->flags member can be set on other cpu without chainlock
being held by that task, i.e. the RMW-Cycle can clear INET_FRAG_EVICTED
bit after we put the element on the evictor private list.

We can crash when walking the 'private' evictor list since an element can
be deleted from list underneath the evictor.

Join work with Nikolay Alexandrov.

Fixes: b13d3cbfb8e8 ("inet: frag: move eviction of queues to work queue")
Reported-by: Johan Schuijt 
Tested-by: Frank Schreuder 
Signed-off-by: Nikolay Alexandrov 
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

ipv4: coding style: comparison for equality with NULL

2015-04-03T16:11:15+00:00

The ipv4 code uses a mixture of coding styles. In some instances check
for NULL pointer is done as x == NULL and sometimes as !x. !x is
preferred according to checkpatch and this patch makes the code
consistent by adopting the latter form.

No changes detected by objdiff.

Signed-off-by: Ian Morris 
Signed-off-by: David S. Miller

net: Convert LIMIT_NETDEBUG to net_dbg_ratelimited

2014-11-11T19:10:31+00:00

Use the more common dynamic_debug capable net_dbg_ratelimited
and remove the LIMIT_NETDEBUG macro.

All messages are still ratelimited.

Some KERN_ uses are changed to KERN_DEBUG.

This may have some negative impact on messages that were
emitted at KERN_INFO that are not not enabled at all unless
DEBUG is defined or dynamic_debug is enabled.  Even so,
these messages are now _not_ emitted by default.

This also eliminates the use of the net_msg_warn sysctl
"/proc/sys/net/core/warnings".  For backward compatibility,
the sysctl is not removed, but it has no function.  The extern
declaration of net_msg_warn is removed from sock.h and made
static in net/core/sysctl_net_core.c

Miscellanea:

o Update the sysctl documentation
o Remove the embedded uses of pr_fmt
o Coalesce format fragments
o Realign arguments

Signed-off-by: Joe Perches 
Signed-off-by: David S. Miller