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  1. 01 5月, 2012 3 次提交
    • E
      net: makes skb_splice_bits() aware of skb->head_frag · 1d0c0b32
      由 Eric Dumazet 提交于 
      __skb_splice_bits() can check if skb to be spliced has its skb->head
mapped to a page fragment, instead of a kmalloc() area.

If so we can avoid a copy of the skb head and get a reference on
underlying page.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Matt Carlson <mcarlson@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1d0c0b32
    • E
      net: make GRO aware of skb->head_frag · d7e8883c
      由 Eric Dumazet 提交于 
      GRO can check if skb to be merged has its skb->head mapped to a page
fragment, instead of a kmalloc() area.

We 'upgrade' skb->head as a fragment in itself

This avoids the frag_list fallback, and permits to build true GRO skb
(one sk_buff and up to 16 fragments), using less memory.

This reduces number of cache misses when user makes its copy, since a
single sk_buff is fetched.

This is a followup of patch "net: allow skb->head to be a page fragment"
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Matt Carlson <mcarlson@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d7e8883c
    • E
      net: allow skb->head to be a page fragment · d3836f21
      由 Eric Dumazet 提交于 
      skb->head is currently allocated from kmalloc(). This is convenient but
has the drawback the data cannot be converted to a page fragment if
needed.

We have three spots were it hurts :

1) GRO aggregation

 When a linear skb must be appended to another skb, GRO uses the
frag_list fallback, very inefficient since we keep all struct sk_buff
around. So drivers enabling GRO but delivering linear skbs to network
stack aren't enabling full GRO power.

2) splice(socket -> pipe).

 We must copy the linear part to a page fragment.
 This kind of defeats splice() purpose (zero copy claim)

3) TCP coalescing.

 Recently introduced, this permits to group several contiguous segments
into a single skb. This shortens queue lengths and save kernel memory,
and greatly reduce probabilities of TCP collapses. This coalescing
doesnt work on linear skbs (or we would need to copy data, this would be
too slow)

Given all these issues, the following patch introduces the possibility
of having skb->head be a fragment in itself. We use a new skb flag,
skb->head_frag to carry this information.

build_skb() is changed to accept a frag_size argument. Drivers willing
to provide a page fragment instead of kmalloc() data will set a non zero
value, set to the fragment size.

Then, on situations we need to convert the skb head to a frag in itself,
we can check if skb->head_frag is set and avoid the copies or various
fallbacks we have.

This means drivers currently using frags could be updated to avoid the
current skb->head allocation and reduce their memory footprint (aka skb
truesize). (thats 512 or 1024 bytes saved per skb). This also makes
bpf/netfilter faster since the 'first frag' will be part of skb linear
part, no need to copy data.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Matt Carlson <mcarlson@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d3836f21
  3. 24 4月, 2012 3 次提交
  5. 22 4月, 2012 1 次提交
  7. 20 4月, 2012 1 次提交
  9. 16 4月, 2012 1 次提交
  11. 11 4月, 2012 1 次提交
  13. 06 4月, 2012 1 次提交
  15. 05 4月, 2012 1 次提交
  17. 29 3月, 2012 1 次提交
  19. 26 3月, 2012 1 次提交
  21. 24 2月, 2012 1 次提交
  23. 14 2月, 2012 1 次提交
  25. 17 12月, 2011 1 次提交
  27. 05 12月, 2011 1 次提交
    • E
      tcp: take care of misalignments · 117632e6
      由 Eric Dumazet 提交于 
      We discovered that TCP stack could retransmit misaligned skbs if a
malicious peer acknowledged sub MSS frame. This currently can happen
only if output interface is non SG enabled : If SG is enabled, tcp
builds headless skbs (all payload is included in fragments), so the tcp
trimming process only removes parts of skb fragments, header stay
aligned.

Some arches cant handle misalignments, so force a head reallocation and
shrink headroom to MAX_TCP_HEADER.

Dont care about misaligments on x86 and PPC (or other arches setting
NET_IP_ALIGN to 0)

This patch introduces __pskb_copy() which can specify the headroom of
new head, and pskb_copy() becomes a wrapper on top of __pskb_copy()
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      117632e6
  29. 23 11月, 2011 1 次提交
  31. 17 11月, 2011 1 次提交
  33. 15 11月, 2011 1 次提交
    • E
      net: introduce build_skb() · b2b5ce9d
      由 Eric Dumazet 提交于 
      One of the thing we discussed during netdev 2011 conference was the idea
to change some network drivers to allocate/populate their skb at RX
completion time, right before feeding the skb to network stack.

In old days, we allocated skbs when populating the RX ring.

This means bringing into cpu cache sk_buff and skb_shared_info cache
lines (since we clear/initialize them), then 'queue' skb->data to NIC.

By the time NIC fills a frame in skb->data buffer and host can process
it, cpu probably threw away the cache lines from its caches, because lot
of things happened between the allocation and final use.

So the deal would be to allocate only the data buffer for the NIC to
populate its RX ring buffer. And use build_skb() at RX completion to
attach a data buffer (now filled with an ethernet frame) to a new skb,
initialize the skb_shared_info portion, and give the hot skb to network
stack.

build_skb() is the function to allocate an skb, caller providing the
data buffer that should be attached to it. Drivers are expected to call
skb_reserve() right after build_skb() to adjust skb->data to the
Ethernet frame (usually skipping NET_SKB_PAD and NET_IP_ALIGN, but some
drivers might add a hardware provided alignment)

Data provided to build_skb() MUST have been allocated by a prior
kmalloc() call, with enough room to add SKB_DATA_ALIGN(sizeof(struct
skb_shared_info)) bytes at the end of the data without corrupting
incoming frame.

data = kmalloc(NET_SKB_PAD + NET_IP_ALIGN + 1536 +
               SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
	       GFP_ATOMIC);
...
skb = build_skb(data);
if (!skb) {
	recycle_data(data);
} else {
	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
	...
}
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Eilon Greenstein <eilong@broadcom.com>
CC: Ben Hutchings <bhutchings@solarflare.com>
CC: Tom Herbert <therbert@google.com>
CC: Jamal Hadi Salim <hadi@mojatatu.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
CC: Thomas Graf <tgraf@infradead.org>
CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b2b5ce9d
  35. 10 11月, 2011 1 次提交
    • J
      net: add wireless TX status socket option · 6e3e939f
      由 Johannes Berg 提交于 
      The 802.1X EAPOL handshake hostapd does requires
knowing whether the frame was ack'ed by the peer.
Currently, we fudge this pretty badly by not even
transmitting the frame as a normal data frame but
injecting it with radiotap and getting the status
out of radiotap monitor as well. This is rather
complex, confuses users (mon.wlan0 presence) and
doesn't work with all hardware.

To get rid of that hack, introduce a real wifi TX
status option for data frame transmissions.

This works similar to the existing TX timestamping
in that it reflects the SKB back to the socket's
error queue with a SCM_WIFI_STATUS cmsg that has
an int indicating ACK status (0/1).

Since it is possible that at some point we will
want to have TX timestamping and wifi status in a
single errqueue SKB (there's little point in not
doing that), redefine SO_EE_ORIGIN_TIMESTAMPING
to SO_EE_ORIGIN_TXSTATUS which can collect more
than just the timestamp; keep the old constant
as an alias of course. Currently the internal APIs
don't make that possible, but it wouldn't be hard
to split them up in a way that makes it possible.

Thanks to Neil Horman for helping me figure out
the functions that add the control messages.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>
      6e3e939f
  37. 04 11月, 2011 1 次提交
    • T
      net: Add back alignment for size for __alloc_skb · bc417e30
      由 Tony Lindgren 提交于 
      Commit 87fb4b7b (net: more
accurate skb truesize) changed the alignment of size. This
can cause problems at least on some machines with NFS root:

Unhandled fault: alignment exception (0x801) at 0xc183a43a
Internal error: : 801 [#1] PREEMPT
Modules linked in:
CPU: 0    Not tainted  (3.1.0-08784-g5eeee4a #733)
pc : [<c02fbba0>]    lr : [<c02fbb9c>]    psr: 60000013
sp : c180fef8  ip : 00000000  fp : c181f580
r10: 00000000  r9 : c044b28c  r8 : 00000001
r7 : c183a3a0  r6 : c1835be0  r5 : c183a412  r4 : 000001f2
r3 : 00000000  r2 : 00000000  r1 : ffffffe6  r0 : c183a43a
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
Control: 0005317f  Table: 10004000  DAC: 00000017
Process swapper (pid: 1, stack limit = 0xc180e270)
Stack: (0xc180fef8 to 0xc1810000)
fee0:                                                       00000024 00000000
ff00: 00000000 c183b9c0 c183b8e0 c044b28c c0507ccc c019dfc4 c180ff2c c0503cf8
ff20: c180ff4c c180ff4c 00000000 c1835420 c182c740 c18349c0 c05233c0 00000000
ff40: 00000000 c00e6bb8 c180e000 00000000 c04dd82c c0507e7c c050cc18 c183b9c0
ff60: c05233c0 00000000 00000000 c01f34f4 c0430d70 c019d364 c04dd898 c04dd898
ff80: c04dd82c c0507e7c c180e000 00000000 c04c584c c01f4918 c04dd898 c04dd82c
ffa0: c04ddd28 c180e000 00000000 c0008758 c181fa60 3231d82c 00000037 00000000
ffc0: 00000000 c04dd898 c04dd82c c04ddd28 00000013 00000000 00000000 00000000
ffe0: 00000000 c04b2224 00000000 c04b21a0 c001056c c001056c 00000000 00000000
Function entered at [<c02fbba0>] from [<c019dfc4>]
Function entered at [<c019dfc4>] from [<c01f34f4>]
Function entered at [<c01f34f4>] from [<c01f4918>]
Function entered at [<c01f4918>] from [<c0008758>]
Function entered at [<c0008758>] from [<c04b2224>]
Function entered at [<c04b2224>] from [<c001056c>]
Code: e1a00005 e3a01028 ebfa7cb0 e35a0000 (e5858028)

Here PC is at __alloc_skb and &shinfo->dataref is unaligned because
skb->end can be unaligned without this patch.

As explained by Eric Dumazet <eric.dumazet@gmail.com>, this happens
only with SLOB, and not with SLAB or SLUB:

* Eric Dumazet <eric.dumazet@gmail.com> [111102 15:56]:
>
> Your patch is absolutely needed, I completely forgot about SLOB :(
>
> since, kmalloc(386) on SLOB gives exactly ksize=386 bytes, not nearest
> power of two.
>
> [   60.305763] malloc(size=385)->ffff880112c11e38 ksize=386 -> nsize=2
> [   60.305921] malloc(size=385)->ffff88007c92ce28 ksize=386 -> nsize=2
> [   60.306898] malloc(size=656)->ffff88007c44ad28 ksize=656 -> nsize=272
> [   60.325385] malloc(size=656)->ffff88007c575868 ksize=656 -> nsize=272
> [   60.325531] malloc(size=656)->ffff88011c777230 ksize=656 -> nsize=272
> [   60.325701] malloc(size=656)->ffff880114011008 ksize=656 -> nsize=272
> [   60.346716] malloc(size=385)->ffff880114142008 ksize=386 -> nsize=2
> [   60.346900] malloc(size=385)->ffff88011c777690 ksize=386 -> nsize=2
Signed-off-by: NTony Lindgren <tony@atomide.com>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      bc417e30
  39. 21 10月, 2011 1 次提交
  41. 20 10月, 2011 1 次提交
  43. 19 10月, 2011 1 次提交
  45. 14 10月, 2011 1 次提交
    • E
      net: more accurate skb truesize · 87fb4b7b
      由 Eric Dumazet 提交于 
      skb truesize currently accounts for sk_buff struct and part of skb head.
kmalloc() roundings are also ignored.

Considering that skb_shared_info is larger than sk_buff, its time to
take it into account for better memory accounting.

This patch introduces SKB_TRUESIZE(X) macro to centralize various
assumptions into a single place.

At skb alloc phase, we put skb_shared_info struct at the exact end of
skb head, to allow a better use of memory (lowering number of
reallocations), since kmalloc() gives us power-of-two memory blocks.

Unless SLUB/SLUB debug is active, both skb->head and skb_shared_info are
aligned to cache lines, as before.

Note: This patch might trigger performance regressions because of
misconfigured protocol stacks, hitting per socket or global memory
limits that were previously not reached. But its a necessary step for a
more accurate memory accounting.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Andi Kleen <ak@linux.intel.com>
CC: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      87fb4b7b
  47. 16 9月, 2011 1 次提交
    • M
      net: copy userspace buffers on device forwarding · 48c83012
      由 Michael S. Tsirkin 提交于 
      dev_forward_skb loops an skb back into host networking
stack which might hang on the memory indefinitely.
In particular, this can happen in macvtap in bridged mode.
Copy the userspace fragments to avoid blocking the
sender in that case.

As this patch makes skb_copy_ubufs extern now,
I also added some documentation and made it clear
the SKBTX_DEV_ZEROCOPY flag automatically instead
of doing it in all callers. This can be made into a separate
patch if people feel it's worth it.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      48c83012
  49. 25 8月, 2011 1 次提交
  51. 21 8月, 2011 1 次提交
  53. 18 8月, 2011 1 次提交
  55. 02 8月, 2011 1 次提交
  57. 22 7月, 2011 1 次提交
  59. 09 7月, 2011 1 次提交
  61. 07 7月, 2011 1 次提交
    • S
      skbuff: skb supports zero-copy buffers · a6686f2f
      由 Shirley Ma 提交于 
      This patch adds userspace buffers support in skb shared info. A new
struct skb_ubuf_info is needed to maintain the userspace buffers
argument and index, a callback is used to notify userspace to release
the buffers once lower device has done DMA (Last reference to that skb
has gone).

If there is any userspace apps to reference these userspace buffers,
then these userspaces buffers will be copied into kernel. This way we
can prevent userspace apps from holding these userspace buffers too long.

Use destructor_arg to point to the userspace buffer info; a new tx flags
SKBTX_DEV_ZEROCOPY is added for zero-copy buffer check.
Signed-off-by: NShirley Ma <xma@...ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a6686f2f
  63. 21 5月, 2011 1 次提交
    • L
      sanitize <linux/prefetch.h> usage · 268bb0ce
      由 Linus Torvalds 提交于 
      Commit e66eed65 ("list: remove prefetching from regular list
iterators") removed the include of prefetch.h from list.h, which
uncovered several cases that had apparently relied on that rather
obscure header file dependency.

So this fixes things up a bit, using

   grep -L linux/prefetch.h $(git grep -l '[^a-z_]prefetchw*(' -- '*.[ch]')
   grep -L 'prefetchw*(' $(git grep -l 'linux/prefetch.h' -- '*.[ch]')

to guide us in finding files that either need <linux/prefetch.h>
inclusion, or have it despite not needing it.

There are more of them around (mostly network drivers), but this gets
many core ones.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      268bb0ce
  65. 18 5月, 2011 1 次提交
    • E
      net: add skb_dst_force() in sock_queue_err_skb() · abb57ea4
      由 Eric Dumazet 提交于 
      Commit 7fee226a (add a noref bit on skb dst) forgot to use
skb_dst_force() on packets queued in sk_error_queue

This triggers following warning, for applications using IP_CMSG_PKTINFO
receiving one error status


------------[ cut here ]------------
WARNING: at include/linux/skbuff.h:457 ip_cmsg_recv_pktinfo+0xa6/0xb0()
Hardware name: 2669UYD
Modules linked in: isofs vboxnetadp vboxnetflt nfsd ebtable_nat ebtables
lib80211_crypt_ccmp uinput xcbc hdaps tp_smapi thinkpad_ec radeonfb fb_ddc
radeon ttm drm_kms_helper drm ipw2200 intel_agp intel_gtt libipw i2c_algo_bit
i2c_i801 agpgart rng_core cfbfillrect cfbcopyarea cfbimgblt video raid10 raid1
raid0 linear md_mod vboxdrv
Pid: 4697, comm: miredo Not tainted 2.6.39-rc6-00569-g5895198c-dirty #22
Call Trace:
 [<c17746b6>] ? printk+0x1d/0x1f
 [<c1058302>] warn_slowpath_common+0x72/0xa0
 [<c15bbca6>] ? ip_cmsg_recv_pktinfo+0xa6/0xb0
 [<c15bbca6>] ? ip_cmsg_recv_pktinfo+0xa6/0xb0
 [<c1058350>] warn_slowpath_null+0x20/0x30
 [<c15bbca6>] ip_cmsg_recv_pktinfo+0xa6/0xb0
 [<c15bbdd7>] ip_cmsg_recv+0x127/0x260
 [<c154f82d>] ? skb_dequeue+0x4d/0x70
 [<c1555523>] ? skb_copy_datagram_iovec+0x53/0x300
 [<c178e834>] ? sub_preempt_count+0x24/0x50
 [<c15bdd2d>] ip_recv_error+0x23d/0x270
 [<c15de554>] udp_recvmsg+0x264/0x2b0
 [<c15ea659>] inet_recvmsg+0xd9/0x130
 [<c1547752>] sock_recvmsg+0xf2/0x120
 [<c11179cb>] ? might_fault+0x4b/0xa0
 [<c15546bc>] ? verify_iovec+0x4c/0xc0
 [<c1547660>] ? sock_recvmsg_nosec+0x100/0x100
 [<c1548294>] __sys_recvmsg+0x114/0x1e0
 [<c1093895>] ? __lock_acquire+0x365/0x780
 [<c1148b66>] ? fget_light+0xa6/0x3e0
 [<c1148b7f>] ? fget_light+0xbf/0x3e0
 [<c1148aee>] ? fget_light+0x2e/0x3e0
 [<c1549f29>] sys_recvmsg+0x39/0x60

Close bug https://bugzilla.kernel.org/show_bug.cgi?id=34622Reported-by: NWitold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      abb57ea4
  67. 31 3月, 2011 1 次提交
  69. 17 3月, 2011 1 次提交
  71. 02 3月, 2011 1 次提交