1. 18 Jul, 2014 12 commits
  2. 17 Jul, 2014 2 commits
    • Linus Torvalds's avatar
      Merge tag 'stable/for-linus-3.16-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip · 59ca9ee4
      Linus Torvalds authored
      Pull Xen fixes from Konrad Rzeszutek Wilk:
       "Two fixes found during migration of PV guests.  David would be the one
        doing this pull but he is on vacation.
      
        Fixes:
         - fix console deadlock when resuming PV guests
         - fix regression hit when ballooning and resuming PV guests"
      
      * tag 'stable/for-linus-3.16-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
        xen/balloon: set ballooned out pages as invalid in p2m
        xen/manage: fix potential deadlock when resuming the console
      59ca9ee4
    • Linus Torvalds's avatar
      Merge tag 'trace-fixes-v3.16-rc5-v2' of... · 22d36854
      Linus Torvalds authored
      Merge tag 'trace-fixes-v3.16-rc5-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
      
      Pull tracing fixes from Steven Rostedt:
       "A few more fixes for ftrace infrastructure.
      
        I was cleaning out my INBOX and found two fixes from zhangwei from a
        year ago that were lost in my mail.  These fix an inconsistency
        between trace_puts() and the way trace_printk() works.  The reason
        this is important to fix is because when trace_printk() doesn't have
        any arguments, it turns into a trace_puts().  Not being able to enable
        a stack trace against trace_printk() because it does not have any
        arguments is quite confusing.  Also, the fix is rather trivial and low
        risk.
      
        While porting some changes to PowerPC I discovered that it still has
        the function graph tracer filter bug that if you also enable stack
        tracing the function graph tracer filter is ignored.  I fixed that up.
      
        Finally, Martin Lau, fixed a bug that would cause readers of the
        ftrace ring buffer to block forever even though it was suppose to be
        NONBLOCK"
      
      This also includes the fix from an earlier pull request:
      
       "Oleg Nesterov fixed a memory leak that happens if a user creates a
        tracing instance, sets up a filter in an event, and then removes that
        instance.  The filter allocates memory that is never freed when the
        instance is destroyed"
      
      * tag 'trace-fixes-v3.16-rc5-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
        ring-buffer: Fix polling on trace_pipe
        tracing: Add TRACE_ITER_PRINTK flag check in __trace_puts/__trace_bputs
        tracing: Fix graph tracer with stack tracer on other archs
        tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputs
        tracing: instance_rmdir() leaks ftrace_event_file->filter
      22d36854
  3. 16 Jul, 2014 7 commits
  4. 15 Jul, 2014 15 commits
    • Martin Lau's avatar
      ring-buffer: Fix polling on trace_pipe · 97b8ee84
      Martin Lau authored
      ring_buffer_poll_wait() should always put the poll_table to its wait_queue
      even there is immediate data available.  Otherwise, the following epoll and
      read sequence will eventually hang forever:
      
      1. Put some data to make the trace_pipe ring_buffer read ready first
      2. epoll_ctl(efd, EPOLL_CTL_ADD, trace_pipe_fd, ee)
      3. epoll_wait()
      4. read(trace_pipe_fd) till EAGAIN
      5. Add some more data to the trace_pipe ring_buffer
      6. epoll_wait() -> this epoll_wait() will block forever
      
      ~ During the epoll_ctl(efd, EPOLL_CTL_ADD,...) call in step 2,
        ring_buffer_poll_wait() returns immediately without adding poll_table,
        which has poll_table->_qproc pointing to ep_poll_callback(), to its
        wait_queue.
      ~ During the epoll_wait() call in step 3 and step 6,
        ring_buffer_poll_wait() cannot add ep_poll_callback() to its wait_queue
        because the poll_table->_qproc is NULL and it is how epoll works.
      ~ When there is new data available in step 6, ring_buffer does not know
        it has to call ep_poll_callback() because it is not in its wait queue.
        Hence, block forever.
      
      Other poll implementation seems to call poll_wait() unconditionally as the very
      first thing to do.  For example, tcp_poll() in tcp.c.
      
      Link: http://lkml.kernel.org/p/20140610060637.GA14045@devbig242.prn2.facebook.com
      
      Cc: stable@vger.kernel.org # 2.6.27
      Fixes: 2a2cc8f7 "ftrace: allow the event pipe to be polled"
      Reviewed-by: default avatarChris Mason <clm@fb.com>
      Signed-off-by: default avatarMartin Lau <kafai@fb.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      97b8ee84
    • Niu Yawei's avatar
      quota: missing lock in dqcache_shrink_scan() · d68aab6b
      Niu Yawei authored
      Commit 1ab6c499 (fs: convert fs shrinkers to new scan/count API)
      accidentally removed locking from quota shrinker. Fix it -
      dqcache_shrink_scan() should use dq_list_lock to protect the
      scan on free_dquots list.
      
      CC: stable@vger.kernel.org
      Fixes: 1ab6c499Signed-off-by: default avatarNiu Yawei <yawei.niu@intel.com>
      Signed-off-by: default avatarJan Kara <jack@suse.cz>
      d68aab6b
    • Mike Snitzer's avatar
      dm cache metadata: do not allow the data block size to change · 048e5a07
      Mike Snitzer authored
      The block size for the dm-cache's data device must remained fixed for
      the life of the cache.  Disallow any attempt to change the cache's data
      block size.
      Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
      Acked-by: default avatarJoe Thornber <ejt@redhat.com>
      Cc: stable@vger.kernel.org
      048e5a07
    • Mike Snitzer's avatar
      dm thin metadata: do not allow the data block size to change · 9aec8629
      Mike Snitzer authored
      The block size for the thin-pool's data device must remained fixed for
      the life of the thin-pool.  Disallow any attempt to change the
      thin-pool's data block size.
      
      It should be noted that attempting to change the data block size via
      thin-pool table reload will be ignored as a side-effect of the thin-pool
      handover that the thin-pool target does during thin-pool table reload.
      
      Here is an example outcome of attempting to load a thin-pool table that
      reduced the thin-pool's data block size from 1024K to 512K.
      
      Before:
      kernel: device-mapper: thin: 253:4: growing the data device from 204800 to 409600 blocks
      
      After:
      kernel: device-mapper: thin metadata: changing the data block size (from 2048 to 1024) is not supported
      kernel: device-mapper: table: 253:4: thin-pool: Error creating metadata object
      kernel: device-mapper: ioctl: error adding target to table
      Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
      Acked-by: default avatarJoe Thornber <ejt@redhat.com>
      Cc: stable@vger.kernel.org
      9aec8629
    • zhangwei(Jovi)'s avatar
      tracing: Add TRACE_ITER_PRINTK flag check in __trace_puts/__trace_bputs · f0160a5a
      zhangwei(Jovi) authored
      The TRACE_ITER_PRINTK check in __trace_puts/__trace_bputs is missing,
      so add it, to be consistent with __trace_printk/__trace_bprintk.
      Those functions are all called by the same function: trace_printk().
      
      Link: http://lkml.kernel.org/p/51E7A7D6.8090900@huawei.com
      
      Cc: stable@vger.kernel.org # 3.11+
      Signed-off-by: default avatarzhangwei(Jovi) <jovi.zhangwei@huawei.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      f0160a5a
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse · 0b632204
      Linus Torvalds authored
      Pull fuse fixes from Miklos Szeredi:
       "This contains miscellaneous fixes"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
        fuse: replace count*size kzalloc by kcalloc
        fuse: release temporary page if fuse_writepage_locked() failed
        fuse: restructure ->rename2()
        fuse: avoid scheduling while atomic
        fuse: handle large user and group ID
        fuse: inode: drop cast
        fuse: ignore entry-timeout on LOOKUP_REVAL
        fuse: timeout comparison fix
      0b632204
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net · 5615f9f8
      Linus Torvalds authored
      Pull networking fixes from David Miller:
      
       1) Bluetooth pairing fixes from Johan Hedberg.
      
       2) ieee80211_send_auth() doesn't allocate enough tail room for the SKB,
          from Max Stepanov.
      
       3) New iwlwifi chip IDs, from Oren Givon.
      
       4) bnx2x driver reads wrong PCI config space MSI register, from Yijing
          Wang.
      
       5) IPV6 MLD Query validation isn't strong enough, from Hangbin Liu.
      
       6) Fix double SKB free in openvswitch, from Andy Zhou.
      
       7) Fix sk_dst_set() being racey with UDP sockets, leading to strange
          crashes, from Eric Dumazet.
      
       8) Interpret the NAPI budget correctly in the new systemport driver,
          from Florian Fainelli.
      
       9) VLAN code frees percpu stats in the wrong place, leading to crashes
          in the get stats handler.  From Eric Dumazet.
      
      10) TCP sockets doing a repair can crash with a divide by zero, because
          we invoke tcp_push() with an MSS value of zero.  Just skip that part
          of the sendmsg paths in repair mode.  From Christoph Paasch.
      
      11) IRQ affinity bug fixes in mlx4 driver from Amir Vadai.
      
      12) Don't ignore path MTU icmp messages with a zero mtu, machines out
          there still spit them out, and all of our per-protocol handlers for
          PMTU can cope with it just fine.  From Edward Allcutt.
      
      13) Some NETDEV_CHANGE notifier invocations were not passing in the
          correct kind of cookie as the argument, from Loic Prylli.
      
      14) Fix crashes in long multicast/broadcast reassembly, from Jon Paul
          Maloy.
      
      15) ip_tunnel_lookup() doesn't interpret wildcard keys correctly, fix
          from Dmitry Popov.
      
      16) Fix skb->sk assigned without taking a reference to 'sk' in
          appletalk, from Andrey Utkin.
      
      17) Fix some info leaks in ULP event signalling to userspace in SCTP,
          from Daniel Borkmann.
      
      18) Fix deadlocks in HSO driver, from Olivier Sobrie.
      
      * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (93 commits)
        hso: fix deadlock when receiving bursts of data
        hso: remove unused workqueue
        net: ppp: don't call sk_chk_filter twice
        mlx4: mark napi id for gro_skb
        bonding: fix ad_select module param check
        net: pppoe: use correct channel MTU when using Multilink PPP
        neigh: sysctl - simplify address calculation of gc_* variables
        net: sctp: fix information leaks in ulpevent layer
        MAINTAINERS: update r8169 maintainer
        net: bcmgenet: fix RGMII_MODE_EN bit
        tipc: clear 'next'-pointer of message fragments before reassembly
        r8152: fix r8152_csum_workaround function
        be2net: set EQ DB clear-intr bit in be_open()
        GRE: enable offloads for GRE
        farsync: fix invalid memory accesses in fst_add_one() and fst_init_card()
        igb: do a reset on SR-IOV re-init if device is down
        igb: Workaround for i210 Errata 25: Slow System Clock
        usbnet: smsc95xx: add reset_resume function with reset operation
        dp83640: Always decode received status frames
        r8169: disable L23
        ...
      5615f9f8
    • Steven Rostedt (Red Hat)'s avatar
      tracing: Fix graph tracer with stack tracer on other archs · 5f8bf2d2
      Steven Rostedt (Red Hat) authored
      Running my ftrace tests on PowerPC, it failed the test that checks
      if function_graph tracer is affected by the stack tracer. It was.
      Looking into this, I found that the update_function_graph_func()
      must be called even if the trampoline function is not changed.
      This is because archs like PowerPC do not support ftrace_ops being
      passed by assembly and instead uses a helper function (what the
      trampoline function points to). Since this function is not changed
      even when multiple ftrace_ops are added to the code, the test that
      falls out before calling update_function_graph_func() will miss that
      the update must still be done.
      
      Call update_function_graph_function() for all calls to
      update_ftrace_function()
      
      Cc: stable@vger.kernel.org # 3.3+
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      5f8bf2d2
    • zhangwei(Jovi)'s avatar
      tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputs · 8abfb872
      zhangwei(Jovi) authored
      Currently trace option stacktrace is not applicable for
      trace_printk with constant string argument, the reason is
      in __trace_puts/__trace_bputs ftrace_trace_stack is missing.
      
      In contrast, when using trace_printk with non constant string
      argument(will call into __trace_printk/__trace_bprintk), then
      trace option stacktrace is workable, this inconstant result
      will confuses users a lot.
      
      Link: http://lkml.kernel.org/p/51E7A7C9.9040401@huawei.com
      
      Cc: stable@vger.kernel.org # 3.10+
      Signed-off-by: default avatarzhangwei(Jovi) <jovi.zhangwei@huawei.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      8abfb872
    • Takashi Iwai's avatar
      ALSA: hda - Fix broken PM due to incomplete i915 initialization · 4da63c6f
      Takashi Iwai authored
      When the initialization of Intel HDMI controller fails due to missing
      i915 kernel symbols (e.g. HD-audio is built in while i915 is module),
      the driver discontinues the probe.  However, since the probe was done
      asynchronously, the driver object still remains, thus the relevant PM
      ops are still called at suspend/resume. This results in the bad access
      to the incomplete audio card object, eventually leads to Oops or stall
      at PM.
      
      This patch adds the missing checks of chip->init_failed flag at each
      PM callback in order to fix the problem above.
      
      Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=79561
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      4da63c6f
    • Olivier Sobrie's avatar
      hso: fix deadlock when receiving bursts of data · 8f9818af
      Olivier Sobrie authored
      When the module sends bursts of data, sometimes a deadlock happens in
      the hso driver when the tty buffer doesn't get the chance to be flushed
      quickly enough.
      
      Remove the endless while loop in function put_rxbuf_data() which is
      called by the urb completion handler.
      If there isn't enough room in the tty buffer, discards all the data
      received in the URB.
      
      Cc: David Miller <davem@davemloft.net>
      Cc: David Laight <David.Laight@ACULAB.COM>
      Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
      Cc: Dan Williams <dcbw@redhat.com>
      Cc: Jan Dumon <j.dumon@option.com>
      Signed-off-by: default avatarOlivier Sobrie <olivier@sobrie.be>
      Acked-by: default avatarAlan Cox <alan@linux.intel.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8f9818af
    • Olivier Sobrie's avatar
      hso: remove unused workqueue · 5c763edf
      Olivier Sobrie authored
      The workqueue "retry_unthrottle_workqueue" is not scheduled anywhere
      in the code. So, remove it.
      Signed-off-by: default avatarOlivier Sobrie <olivier@sobrie.be>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5c763edf
    • Linus Torvalds's avatar
      Merge tag 'firewire-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394 · 1b81e881
      Linus Torvalds authored
      Pull firewire fix from Stefan Richter:
       "The 1394 drivers cannot and are not supposed to be built on platforms
        which don't provide the DMA mapping API (regression since v3.16-rc1
        with CONFIG_COMPILE_TEST=y on some architectures)"
      
      * tag 'firewire-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
        firewire: IEEE 1394 (FireWire) support should depend on HAS_DMA
      1b81e881
    • Linus Torvalds's avatar
      Merge git://git.kvack.org/~bcrl/aio-fixes · 8ec8ba8e
      Linus Torvalds authored
      Pull another aio fix from Ben LaHaise:
       "put_reqs_available() can now be called from within irq context, which
        means that it (and its sibling function get_reqs_available()) now need
        to be irq-safe, not just preempt-safe"
      
      * git://git.kvack.org/~bcrl/aio-fixes:
        aio: protect reqs_available updates from changes in interrupt handlers
      8ec8ba8e
    • Sasha Levin's avatar
      net/l2tp: don't fall back on UDP [get|set]sockopt · 3cf521f7
      Sasha Levin authored
      The l2tp [get|set]sockopt() code has fallen back to the UDP functions
      for socket option levels != SOL_PPPOL2TP since day one, but that has
      never actually worked, since the l2tp socket isn't an inet socket.
      
      As David Miller points out:
      
        "If we wanted this to work, it'd have to look up the tunnel and then
         use tunnel->sk, but I wonder how useful that would be"
      
      Since this can never have worked so nobody could possibly have depended
      on that functionality, just remove the broken code and return -EINVAL.
      Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Acked-by: default avatarJames Chapman <jchapman@katalix.com>
      Acked-by: default avatarDavid Miller <davem@davemloft.net>
      Cc: Phil Turnbull <phil.turnbull@oracle.com>
      Cc: Vegard Nossum <vegard.nossum@oracle.com>
      Cc: Willy Tarreau <w@1wt.eu>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3cf521f7
  5. 14 Jul, 2014 4 commits
    • Christoph Schulz's avatar
      net: ppp: don't call sk_chk_filter twice · 3916a319
      Christoph Schulz authored
      Commit 568f194e ("net: ppp: use
      sk_unattached_filter api") causes sk_chk_filter() to be called twice when
      setting a PPP pass or active filter. This applies to both the generic PPP
      subsystem implemented by drivers/net/ppp/ppp_generic.c and the ISDN PPP
      subsystem implemented by drivers/isdn/i4l/isdn_ppp.c. The first call is from
      within get_filter(). The second one is through the call chain
      
        ppp_ioctl() or isdn_ppp_ioctl()
        --> sk_unattached_filter_create()
            --> __sk_prepare_filter()
                --> sk_chk_filter()
      
      The first call from within get_filter() should be deleted as get_filter() is
      called just before calling sk_unattached_filter_create() later on, which
      eventually calls sk_chk_filter() anyway.
      
      For 3.15.x, this proposed change is a bugfix rather than a pure optimization as
      in that branch, sk_chk_filter() may replace filter codes by other codes which
      are not recognized when executing sk_chk_filter() a second time. So with
      3.15.x, if sk_chk_filter() is called twice, the second invocation may yield
      EINVAL (this depends on the filter codes found in the filter to be set, but
      because the replacement is done for frequently used codes, this is almost
      always the case). The net effect is that setting pass and/or active PPP filters
      does not work anymore, since sk_unattached_filter_create() always returns
      EINVAL due to the second call to sk_chk_filter(), regardless whether the filter
      was originally sane or not.
      Signed-off-by: default avatarChristoph Schulz <develop@kristov.de>
      Acked-by: default avatarDaniel Borkmann <dborkman@redhat.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      3916a319
    • Jason Wang's avatar
      mlx4: mark napi id for gro_skb · 32b333fe
      Jason Wang authored
      Napi id was not marked for gro_skb, this will lead rx busy loop won't
      work correctly since they stack never try to call low latency receive
      method because of a zero socket napi id. Fix this by marking napi id
      for gro_skb.
      
      The transaction rate of 1 byte netperf tcp_rr gets about 50% increased
      (from 20531.68 to 30610.88).
      
      Cc: Amir Vadai <amirv@mellanox.com>
      Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      32b333fe
    • Nikolay Aleksandrov's avatar
      bonding: fix ad_select module param check · 548d28bd
      Nikolay Aleksandrov authored
      Obvious copy/paste error when I converted the ad_select to the new
      option API. "lacp_rate" there should be "ad_select" so we can get the
      proper value.
      
      CC: Jay Vosburgh <j.vosburgh@gmail.com>
      CC: Veaceslav Falico <vfalico@gmail.com>
      CC: Andy Gospodarek <andy@greyhouse.net>
      CC: David S. Miller <davem@davemloft.net>
      
      Fixes: 9e5f5eeb ("bonding: convert ad_select to use the new option
      API")
      Reported-by: default avatarKarim Scheik <karim.scheik@prisma-solutions.at>
      Signed-off-by: default avatarNikolay Aleksandrov <nikolay@redhat.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      548d28bd
    • Christoph Schulz's avatar
      net: pppoe: use correct channel MTU when using Multilink PPP · a8a3e41c
      Christoph Schulz authored
      The PPP channel MTU is used with Multilink PPP when ppp_mp_explode() (see
      ppp_generic module) tries to determine how big a fragment might be. According
      to RFC 1661, the MTU excludes the 2-byte PPP protocol field, see the
      corresponding comment and code in ppp_mp_explode():
      
      		/*
      		 * hdrlen includes the 2-byte PPP protocol field, but the
      		 * MTU counts only the payload excluding the protocol field.
      		 * (RFC1661 Section 2)
      		 */
      		mtu = pch->chan->mtu - (hdrlen - 2);
      
      However, the pppoe module *does* include the PPP protocol field in the channel
      MTU, which is wrong as it causes the PPP payload to be 1-2 bytes too big under
      certain circumstances (one byte if PPP protocol compression is used, two
      otherwise), causing the generated Ethernet packets to be dropped. So the pppoe
      module has to subtract two bytes from the channel MTU. This error only
      manifests itself when using Multilink PPP, as otherwise the channel MTU is not
      used anywhere.
      
      In the following, I will describe how to reproduce this bug. We configure two
      pppd instances for multilink PPP over two PPPoE links, say eth2 and eth3, with
      a MTU of 1492 bytes for each link and a MRRU of 2976 bytes. (This MRRU is
      computed by adding the two link MTUs and subtracting the MP header twice, which
      is 4 bytes long.) The necessary pppd statements on both sides are "multilink
      mtu 1492 mru 1492 mrru 2976". On the client side, we additionally need "plugin
      rp-pppoe.so eth2" and "plugin rp-pppoe.so eth3", respectively; on the server
      side, we additionally need to start two pppoe-server instances to be able to
      establish two PPPoE sessions, one over eth2 and one over eth3. We set the MTU
      of the PPP network interface to the MRRU (2976) on both sides of the connection
      in order to make use of the higher bandwidth. (If we didn't do that, IP
      fragmentation would kick in, which we want to avoid.)
      
      Now we send a ICMPv4 echo request with a payload of 2948 bytes from client to
      server over the PPP link. This results in the following network packet:
      
         2948 (echo payload)
       +    8 (ICMPv4 header)
       +   20 (IPv4 header)
      ---------------------
         2976 (PPP payload)
      
      These 2976 bytes do not exceed the MTU of the PPP network interface, so the
      IP packet is not fragmented. Now the multilink PPP code in ppp_mp_explode()
      prepends one protocol byte (0x21 for IPv4), making the packet one byte bigger
      than the negotiated MRRU. So this packet would have to be divided in three
      fragments. But this does not happen as each link MTU is assumed to be two bytes
      larger. So this packet is diveded into two fragments only, one of size 1489 and
      one of size 1488. Now we have for that bigger fragment:
      
         1489 (PPP payload)
       +    4 (MP header)
       +    2 (PPP protocol field for the MP payload (0x3d))
       +    6 (PPPoE header)
      --------------------------
         1501 (Ethernet payload)
      
      This packet exceeds the link MTU and is discarded.
      
      If one configures the link MTU on the client side to 1501, one can see the
      discarded Ethernet frames with tcpdump running on the client. A
      
      ping -s 2948 -c 1 192.168.15.254
      
      leads to the smaller fragment that is correctly received on the server side:
      
      (tcpdump -vvvne -i eth3 pppoes and ppp proto 0x3d)
      52:54:00:ad:87:fd > 52:54:00:79:5c:d0, ethertype PPPoE S (0x8864),
        length 1514: PPPoE  [ses 0x3] MLPPP (0x003d), length 1494: seq 0x000,
        Flags [end], length 1492
      
      and to the bigger fragment that is not received on the server side:
      
      (tcpdump -vvvne -i eth2 pppoes and ppp proto 0x3d)
      52:54:00:70:9e:89 > 52:54:00:5d:6f:b0, ethertype PPPoE S (0x8864),
        length 1515: PPPoE  [ses 0x5] MLPPP (0x003d), length 1495: seq 0x000,
        Flags [begin], length 1493
      
      With the patch below, we correctly obtain three fragments:
      
      52:54:00:ad:87:fd > 52:54:00:79:5c:d0, ethertype PPPoE S (0x8864),
        length 1514: PPPoE  [ses 0x1] MLPPP (0x003d), length 1494: seq 0x000,
        Flags [begin], length 1492
      52:54:00:70:9e:89 > 52:54:00:5d:6f:b0, ethertype PPPoE S (0x8864),
        length 1514: PPPoE  [ses 0x1] MLPPP (0x003d), length 1494: seq 0x000,
        Flags [none], length 1492
      52:54:00:ad:87:fd > 52:54:00:79:5c:d0, ethertype PPPoE S (0x8864),
        length 27: PPPoE  [ses 0x1] MLPPP (0x003d), length 7: seq 0x000,
        Flags [end], length 5
      
      And the ICMPv4 echo request is successfully received at the server side:
      
      IP (tos 0x0, ttl 64, id 21925, offset 0, flags [DF], proto ICMP (1),
        length 2976)
          192.168.222.2 > 192.168.15.254: ICMP echo request, id 30530, seq 0,
            length 2956
      
      The bug was introduced in commit c9aa6895
      ("[PPPOE]: Advertise PPPoE MTU") from the very beginning. This patch applies
      to 3.10 upwards but the fix can be applied (with minor modifications) to
      kernels as old as 2.6.32.
      Signed-off-by: default avatarChristoph Schulz <develop@kristov.de>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      a8a3e41c