Commit Graph

264578 Commits

Author SHA1 Message Date
Thomas Hellstrom
6ea77d1384 vmwgfx: Minor cleanups
As suggested by Konrad Rzeszutek Wilk

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:36 +01:00
Thomas Hellstrom
e5ed157d93 vmwgfx: Bump driver minor to advertise support for new ioctls.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:34 +01:00
Jakob Bornecrantz
c337ada7e7 vmwgfx: Be more strict with fb depths when using screen objects
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:33 +01:00
Thomas Hellstrom
5bb39e8181 vmwgfx: Handle device surface memory limit
Make surfaces swappable. Make sure we honor the maximum amount of surface
memory the device accepts. This is done by potentially reading back surface
contents not used by the current command submission and storing it
locally in buffer objects.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:31 +01:00
Thomas Hellstrom
90ff18bc3a vmwgfx: Make sure we always have a user-space handle to use for objects that are backing kms framebuffers.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:26 +01:00
Thomas Hellstrom
f18c8840be vmwgfx: Optimize the command submission resource list
Use a list for resources referenced during command submission, instead of
an array.
As long as we don't implement parallell command submission this works fine
and simplifies things a bit.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:23 +01:00
Thomas Hellstrom
e2fa3a7683 vmwgfx: Fix up query processing
Previously, query results could be placed in any buffer object, but since
we didn't allow pinned buffer objects, query results could be written when
that buffer was evicted, corrupting data in other buffers.

Now, require that buffers holding query results are no more than two pages
large, and allow one single pinned such buffer. When the command submission
code encounters query result structures in other buffers, the queries in the
pinned buffer will be finished using a query barrier for the last hardware
context using the buffer. Also if the command submission code detects
that a new hardware context is used for queries, all queries of the previous
hardware context is also flushed. Currently we use waiting for a no-op
occlusion query as a query barrier for a specific context.

The query buffer is also flushed and unpinned on context destructions,
master drops and before scanout bo placement.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:22 +01:00
Thomas Hellstrom
e93daed8e2 vmwgfx: Allow reference and unreference of NULL fence objects.
The execbuf utils may call reference on NULL fence objects.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:21 +01:00
Thomas Hellstrom
b37a6b9ad0 vmwgfx: minor dmabuf utilities cleanup
Add / fix some function comments.
Don't move out an fbdev framebuffer when unused. Just unpin.
Only have a single function that computes a SVGAGuestPtr from the buffer's
current placement, and make it more versatile by accepting a
struct ttm_buffer_object

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:20 +01:00
Jakob Bornecrantz
0cff60c625 vmwgfx: Disallow user space to send present and readback commands
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:18 +01:00
Jakob Bornecrantz
2fcd5a73bf vmwgfx: Add present and readback ioctls
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:17 +01:00
Jakob Bornecrantz
44031d25cc vmwgfx: Place overlays in GMR area if we can
When we hae screen objects we are allowed to place the overlay source
in the GMR area, do this as this will save precious VRAM.

Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:16 +01:00
Jakob Bornecrantz
01e81419ce vmwgfx: Drop 3D Legacy Display Unit support
Since 3D requires HWv8 and screen objects is always available on those
hosts we only need the screen objects path for surfaces.

Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:15 +01:00
Thomas Hellstrom
b7b70024d9 vmwgfx: Require HWV8 for 3d support
On lower versions, the way we mix 2D and 3D may be too slow.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:14 +01:00
Jakob Bornecrantz
56d1c78df5 vmwgfx: Add screen object support
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:14 +01:00
Jakob Bornecrantz
d991ef0395 vmwgfx: Add dmabuf helper functions for pinning
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:13 +01:00
Jakob Bornecrantz
626ab771c2 vmwgfx: Refactor common display unit functions to shared file
More preparation for Screen Object support.

Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:12 +01:00
Jakob Bornecrantz
4084fb89e6 vmwgfx: Expand the command checker to cover screen object commands
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:12 +01:00
Jakob Bornecrantz
5deb65cf83 vmwgfx: Break out dirty submission code
In preperation for screen objects, still leaves the delayed workqueue
for surface updates in place.

Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:11 +01:00
Thomas Hellstrom
922ade0d16 vmwgfx: Break out execbuf command processing
This will make it easier to execute commands operating on user-space
resources but generated by the kernel.

JB: Added tracking if the sw_context was called from the kernel or userspace.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:11 +01:00
Jakob Bornecrantz
6070e9fa6d vmwgfx: Some comments and BUG_ON
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:10 +01:00
Jakob Bornecrantz
5f898d99de vmwgfx: Make sure the reserved area is at the start of vram
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:09 +01:00
Jakob Bornecrantz
497a3ff987 vmwgfx: Add comments for buffer pinning code
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:09 +01:00
Jakob Bornecrantz
de12d44fca vmwgfx: Document vmw_fifo_reserve
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:08 +01:00
Jakob Bornecrantz
8d3713ea9e vmwgfx: Update register files to latest from vmware-sdk
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:08 +01:00
Thomas Hellstrom
4d79893788 ttm: export ttm_bo_create
Used by the vmwgfx driver.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-05 10:17:07 +01:00
Jason Gerecke
d6069dae47 Input: wacom - revert "Cintiq 21UX2 does not have menu strips"
This reverts commit 71c86ce597.
The 21UX2 does have touchstrips, but they are in a somewhat-
hidden location.

Signed-off-by: Jason Gerecke <killertofu@gmail.com>
Acked-by: Ping Cheng <pinglinux@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2011-10-04 22:54:05 -07:00
Yan, Zheng
1e5289e121 tcp: properly update lost_cnt_hint during shifting
lost_skb_hint is used by tcp_mark_head_lost() to mark the first unhandled skb.
lost_cnt_hint is the number of packets or sacked packets before the lost_skb_hint;
When shifting a skb that is before the lost_skb_hint, if tcp_is_fack() is ture,
the skb has already been counted in the lost_cnt_hint; if tcp_is_fack() is false,
tcp_sacktag_one() will increase the lost_cnt_hint. So tcp_shifted_skb() does not
need to adjust the lost_cnt_hint by itself. When shifting a skb that is equal to
lost_skb_hint, the shifted packets will not be counted by tcp_mark_head_lost().
So tcp_shifted_skb() should adjust the lost_cnt_hint even tcp_is_fack(tp) is true.

Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-04 23:31:24 -04:00
Yan, Zheng
260fcbeb1a tcp: properly handle md5sig_pool references
tcp_v4_clear_md5_list() assumes that multiple tcp md5sig peers
only hold one reference to md5sig_pool. but tcp_v4_md5_do_add()
increases use count of md5sig_pool for each peer. This patch
makes tcp_v4_md5_do_add() only increases use count for the first
tcp md5sig peer.

Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-04 23:31:24 -04:00
David Ward
cb2d0f3e96 macvlan/macvtap: Fix unicast between macvtap interfaces in bridge mode
Packets should always be forwarded to the lowerdev using dev_forward_skb.
vlan->forward is for packets being forwarded directly to another macvlan/
macvtap device (used for multicast in bridge mode).

Reported-and-tested-by: Shlomo Pongratz <shlomop@mellanox.com>
Signed-off-by: David Ward <david.ward@ll.mit.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-04 23:31:23 -04:00
Linus Torvalds
976d167615 Linux 3.1-rc9 2011-10-04 18:11:50 -07:00
Linus Torvalds
8a04b45367 Merge git://github.com/davem330/net
* git://github.com/davem330/net:
  pch_gbe: Fixed the issue on which a network freezes
  pch_gbe: Fixed the issue on which PC was frozen when link was downed.
  make PACKET_STATISTICS getsockopt report consistently between ring and non-ring
  net: xen-netback: correctly restart Tx after a VM restore/migrate
  bonding: properly stop queuing work when requested
  can bcm: fix incomplete tx_setup fix
  RDSRDMA: Fix cleanup of rds_iw_mr_pool
  net: Documentation: Fix type of variables
  ibmveth: Fix oops on request_irq failure
  ipv6: nullify ipv6_ac_list and ipv6_fl_list when creating new socket
  cxgb4: Fix EEH on IBM P7IOC
  can bcm: fix tx_setup off-by-one errors
  MAINTAINERS: tehuti: Alexander Indenbaum's address bounces
  dp83640: reduce driver noise
  ptp: fix L2 event message recognition
2011-10-04 10:37:06 -07:00
Linus Torvalds
a8062e421f Merge branch 'fix/asoc' of git://github.com/tiwai/sound
* 'fix/asoc' of git://github.com/tiwai/sound:
  ASoC: omap_mcpdm_remove cannot be __devexit
  ASoC: Fix setting update bits for WM8753_LADC and WM8753_RADC
  ASoC: use a valid device for dev_err() in Zylonite
2011-10-04 09:59:22 -07:00
Linus Torvalds
1fd2a850ec Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux
* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/radeon/kms: fix channel_remap setup (v2)
  drm/radeon: Set cursor x/y to 0 when x/yorigin > 0.
  drm/radeon: Update AVIVO cursor coordinate origin before x/yorigin calculation.
  drm/radeon: Simplify cursor x/yorigin calculation.
  drm/radeon/kms: fix cursor image off-by-one error
  drm/radeon/kms: Fix logic error in DP HPD handler
  drm/radeon/kms: add retry limits for native DP aux defer
  drm/radeon/kms: fix regression in DP aux defer handling
2011-10-04 09:54:18 -07:00
Linus Torvalds
f8451c3f15 Merge branch 'spi/merge' of git://git.secretlab.ca/git/linux-2.6
* 'spi/merge' of git://git.secretlab.ca/git/linux-2.6:
  spi-topcliff-pch: Fix overrun issue
  spi-topcliff-pch: Add recovery processing in case FIFO overrun error occurs
  spi-topcliff-pch: Fix CPU read complete condition issue
  spi-topcliff-pch: Fix SSN Control issue
  spi-topcliff-pch: add tx-memory clear after complete transmitting
2011-10-04 09:52:56 -07:00
Jon Mason
5f39e6705f PCI: Disable MPS configuration by default
Add the ability to disable PCI-E MPS turning and using the BIOS
configured MPS defaults.  Due to the number of issues recently
discovered on some x86 chipsets, make this the default behavior.

Also, add the option for peer to peer DMA MPS configuration.  Peer to
peer DMA is outside the scope of this patch, but MPS configuration could
prevent it from working by having the MPS on one root port different
than the MPS on another.  To work around this, simply make the system
wide MPS the smallest possible value (128B).

Signed-off-by: Jon Mason <mason@myri.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-04 09:52:28 -07:00
Alex Deucher
12d5180bd7 drm/radeon/kms: fix channel_remap setup (v2)
Most asics just use the hw default value which requires
no explicit programming.  For those that need a different
value, the vbios will program it properly.  As such,
there's no need to program these registers explicitly
in the driver.  Changing MC_SHARED_CHREMAP requires a reload
of all data in vram otherwise its contents will be scambled.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=40103

v2: drop now unused channel_remap functions.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-10-04 17:24:14 +01:00
Tomoya MORINAGA
f3e03e2eb0 spi-topcliff-pch: Fix overrun issue
We found that adding load, Rx data sometimes drops.(with DMA transfer mode)
The cause is that before starting Rx-DMA processing, Tx-DMA processing starts.
This causes FIFO overrun occurs.

This patch fixes the issue by modifying FIFO tx-threshold and DMA descriptor
size like below.

                      Current                   this patch
Rx-descriptor   4Byte+12Byte*341    -->    12Byte*340-4Byte-12Byte
Rx-threshold                   (Not modified)
Tx-descriptor   4Byte+12Byte*341    -->    16Byte-12Byte*340
Rx-threshold    12Byte              -->    2Byte

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2011-10-04 10:10:50 -06:00
Tomoya MORINAGA
25e803f9c3 spi-topcliff-pch: Add recovery processing in case FIFO overrun error occurs
Add recovery processing in case FIFO overrun error occurs with DMA transfer mode.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2011-10-04 10:10:50 -06:00
Tomoya MORINAGA
373b0eb64b spi-topcliff-pch: Fix CPU read complete condition issue
We found Rx data sometimes drops.(with non-DMA transfer mode)
The cause is read complete condition is not true.

This patch fixes the issue.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2011-10-04 10:10:50 -06:00
Tomoya MORINAGA
8b7aa961a8 spi-topcliff-pch: Fix SSN Control issue
During processing 1 command/data series,
SSN should keep LOW.
However, currently, SSN becomes HIGH.
This patch fixes the issue.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2011-10-04 10:10:50 -06:00
Tomoya MORINAGA
27504be5c1 spi-topcliff-pch: add tx-memory clear after complete transmitting
Currently, in case of reading date from SPI flash,
command is sent twice.
The cause is that tx-memory clear processing is missing .
This patch adds the tx-momory clear processing.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2011-10-04 10:10:50 -06:00
Takashi Iwai
05faadcf59 lis3: fix regression of HP DriveGuard with 8bit chip
Commit 2a7fade7e0 ("hwmon: lis3: Power on corrections") caused a
regression on HP laptops with 8bit chip.  Writing CTRL2_BOOT_8B bit seems
clearing the BIOS setup, and no proper interrupt for DriveGuard will be
triggered any more.

Since the init code there is basically only for embedded devices, put a
pdata check so that the problematic initialization will be skipped for
hp_accel stuff.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: Eric Piel <eric.piel@tremplin-utc.net>
Cc: Samu Onkalo <samu.p.onkalo@nokia.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-03 20:51:51 -07:00
Linus Torvalds
0f86267b79 Merge branch 'hwmon-for-linus' of git://github.com/groeck/linux
* 'hwmon-for-linus' of git://github.com/groeck/linux:
  hwmon: (coretemp) Avoid leaving around dangling pointer
  hwmon: (coretemp) Fixup platform device ID change
2011-10-03 12:54:56 -07:00
Linus Torvalds
0d617928f5 Merge git://github.com/davem330/ide
* git://github.com/davem330/ide:
  ide-disk: Fix request requeuing
2011-10-03 12:53:43 -07:00
Linus Torvalds
7fd21be75d Merge branch 'btrfs-3.0' of git://github.com/chrismason/linux
* 'btrfs-3.0' of git://github.com/chrismason/linux:
  Btrfs: force a page fault if we have a shorty copy on a page boundary
2011-10-03 12:17:44 -07:00
Borislav Petkov
2c8fc86760 ide-disk: Fix request requeuing
Simon Kirby reported that on his RAID setup with idedisk underneath
the box OOMs after a couple of days of runtime. Running with
CONFIG_DEBUG_KMEMLEAK pointed to idedisk_prep_fn() which unconditionally
allocates an ide_cmd struct. However, ide_requeue_and_plug() can be
called more than once per request, either from the request issue or the
IRQ handler path and do blk_peek_request() ends up in idedisk_prep_fn()
repeatedly, allocating a struct ide_cmd everytime and "forgetting" the
previous pointer.

Make sure the code reuses the old allocated chunk.

Reported-and-tested-by: Simon Kirby <sim@hostway.ca>
Cc: <stable@kernel.org> [ 39.x, 3.0.x ]
Link: http://marc.info/?l=linux-kernel&m=131667641517919
Link: http://lkml.kernel.org/r/20110922072643.GA27232@hostway.ca
Signed-off-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-03 14:28:18 -04:00
Toshiharu Okada
805e969f61 pch_gbe: Fixed the issue on which a network freezes
The pch_gbe driver has an issue which a network stops,
when receiving traffic is high.
In the case, The link down and up are necessary to return a network.

This patch fixed this issue.

Signed-off-by: Toshiharu Okada <toshiharu-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-03 14:20:39 -04:00
Toshiharu Okada
5f3a114190 pch_gbe: Fixed the issue on which PC was frozen when link was downed.
When a link was downed during network use,
there is an issue on which PC freezes.

This patch fixed this issue.

Signed-off-by: Toshiharu Okada <toshiharu-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-03 14:20:39 -04:00
Willem de Bruijn
7091fbd82c make PACKET_STATISTICS getsockopt report consistently between ring and non-ring
This is a minor change.

Up until kernel 2.6.32, getsockopt(fd, SOL_PACKET, PACKET_STATISTICS,
...) would return total and dropped packets since its last invocation. The
introduction of socket queue overflow reporting [1] changed drop
rate calculation in the normal packet socket path, but not when using a
packet ring. As a result, the getsockopt now returns different statistics
depending on the reception method used. With a ring, it still returns the
count since the last call, as counts are incremented in tpacket_rcv and
reset in getsockopt. Without a ring, it returns 0 if no drops occurred
since the last getsockopt and the total drops over the lifespan of
the socket otherwise. The culprit is this line in packet_rcv, executed
on a drop:

drop_n_acct:
        po->stats.tp_drops = atomic_inc_return(&sk->sk_drops);

As it shows, the new drop number it taken from the socket drop counter,
which is not reset at getsockopt. I put together a small example
that demonstrates the issue [2]. It runs for 10 seconds and overflows
the queue/ring on every odd second. The reported drop rates are:
ring: 16, 0, 16, 0, 16, ...
non-ring: 0, 15, 0, 30, 0, 46, 0, 60, 0 , 74.

Note how the even ring counts monotonically increase. Because the
getsockopt adds tp_drops to tp_packets, total counts are similarly
reported cumulatively. Long story short, reinstating the original code, as
the below patch does, fixes the issue at the cost of additional per-packet
cycles. Another solution that does not introduce per-packet overhead
is be to keep the current data path, record the value of sk_drops at
getsockopt() at call N in a new field in struct packetsock and subtract
that when reporting at call N+1. I'll be happy to code that, instead,
it's just more messy.

[1] http://patchwork.ozlabs.org/patch/35665/
[2] http://kernel.googlecode.com/files/test-packetsock-getstatistics.c

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-03 14:18:26 -04:00