Blamed commit only dealt with applications issuing small writes.

Issue here is that we allow to force memory schedule for the sk_buff
allocation, but we have no guarantee that sendmsg() is able to
copy some payload in it.

In this patch, I make sure the socket can use up to tcp_wmem[0] bytes.

For example, if we consider tcp_wmem[0] = 4096 (default on x86),
and initial skb->truesize being 1280, tcp_sendmsg() is able to
copy up to 2816 bytes under memory pressure.

Before this patch a sendmsg() sending more than 2816 bytes
would either block forever (if persistent memory pressure),
or return -EAGAIN.

For bigger MTU networks, it is advised to increase tcp_wmem[0]
to avoid sending too small packets.

v2: deal with zero copy paths.

Fixes: 8e4d980a ("tcp: fix behavior for epoll edge trigger")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Wei Wang <weiwan@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

sk_forced_mem_schedule() has a bug similar to ones fixed
in commit 7c80b038 ("net: fix sk_wmem_schedule() and
sk_rmem_schedule() errors")

While this bug has little chance to trigger in old kernels,
we need to fix it before the following patch.

Fixes: d83769a5 ("tcp: fix possible deadlock in tcp_send_fin()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Raju Lakkaraju says:

====================
net: lan743x: PCI11010 / PCI11414 devices Enhancements

This patch series continues with the addition of supported features
for the Ethernet function of the PCI11010 / PCI11414 devices to
the LAN743x driver.
====================

Link: https://lore.kernel.org/r/20220616041226.26996-1-Raju.Lakkaraju@microchip.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Add support to Master-Slave configuration and state
Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add SGMII access read and write functions
Add support to SGMII 1G and 2.5G for PCI11010/PCI11414 chips
Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add support to Magic Packet Detection with Secure-ON for PCI11010/PCI11414 chips
Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add support to LAN743x common register dump
Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Alvin Šipraga says:

====================
net: dsa: realtek: rtl8365mb: improve handling of PHY modes

This series introduces some minor cleanup of the driver and improves the
handling of PHY interface modes to break the assumption that CPU ports
are always over an external interface, and the assumption that user
ports are always using an internal PHY.
====================

Link: https://lore.kernel.org/r/20220615225116.432283-1-alvin@pqrs.dkSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Realtek switches in the rtl8365mb family always have at least one port
with a so-called external interface, supporting PHY interface modes such
as RGMII or SGMII. The purpose of this patch is to improve the driver's
handling of these ports.

A new struct rtl8365mb_chip_info is introduced together with a static
array of such structs. An instance of this struct is added for each
supported switch, distinguished by its chip ID and version. Embedded in
each chip_info struct is an array of struct rtl8365mb_extint, describing
the external interfaces available. This is more specific than the old
rtl8365mb_extint_port_map, which was only valid for switches with up to
6 ports.

The struct rtl8365mb_extint also contains a bitmask of supported PHY
interface modes, which allows the driver to distinguish which ports
support RGMII. This corrects a previous mistake in the driver whereby it
was assumed that any port with an external interface supports RGMII.
This is not actually the case: for example, the RTL8367S has two
external interfaces, only the second of which supports RGMII. The first
supports only SGMII and HSGMII. This new design will make it easier to
add support for other interface modes.

Finally, rtl8365mb_phylink_get_caps() is fixed up to return supported
capabilities based on the external interface properties described above.
This addresses Vladimir's point in the linked thread that the
capabilities are not actually a function of the DSA port type: Although
most typical applications will treat the ports with internal PHY as user
ports, there is no actual hardware limitation preventing one from using
them as a CPU port. Equally, ports with external interface(s) may well
be treated as user ports, even though it is typical to use those ports
as CPU ports.

Link: https://lore.kernel.org/netdev/20220510192301.5djdt3ghoavxulhl@bang-olufsen.dk/Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The variable is just assigned the value of a macro, so it can be
removed.
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The maximum number of ports is actually 11, according to two
observations:

1. The highest port ID used in the vendor driver is 10. Since port IDs
   are indexed from 0, and since DSA follows the same numbering system,
   this means up to 11 ports are to be presumed.

2. The registers with port mask fields always amount to a maximum port
   mask of 0x7FF, corresponding to a maximum 11 ports.

In view of this, I also deleted the comment.
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Reviewed-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

There is no real need for this variable: the line change interrupt mask
is sufficiently masked out when getting linkup_ind and linkdown_ind in
the interrupt handler.
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The official name of this switch is RTL8367RB-VB, not RTL8367RB. There
is also an RTL8367RB-VC which is rather different. Change the name of
the CHIP_ID/_VER macros for reasons of consistency.
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Reviewed-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Alex Elder says:

====================
net: ipa: more multi-channel event ring work

This series makes a little more progress toward supporting multiple
channels with a single event ring.  The first removes the assumption
that consecutive events are associated with the same RX channel.

The second derives the channel associated with an event from the
event itself, and the next does a small cleanup enabled by that.

The fourth causes updates to occur for every event processed (rather
once).  And the final patch does a little more rework to make TX
completion have more in common with RX completion.
====================

Link: https://lore.kernel.org/r/20220615165929.5924-1-elder@linaro.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Move the processing done for TX channels in gsi_channel_update()
into gsi_evt_ring_rx_update().  The called function is called for
both RX and TX channels, so rename it to be gsi_evt_ring_update().
As a result, this code no longer assumes events in an event ring are
associated with just one channel.

Because all events in a ring are handled in that function, we can
move the call to gsi_trans_move_complete() there, and can ring the
event ring doorbell there as well after all new events in the ring
have been processed.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

When an RX transaction completes, we update the trans->len field to
contain the actual number of bytes received.  This is done in a loop
in gsi_evt_ring_rx_update().

Change that function so it checks the data transfer direction
recorded in the transaction, and only updates trans->len for RX
transfers.

Then call it unconditionally.  This means events for TX endpoints
will run through the loop without otherwise doing anything, but
this will change shortly.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The only reason the event ring's channel pointer is needed in
gsi_evt_ring_rx_update() is so we can get at its GSI pointer.

We can pass the GSI pointer as an argument, along with the event
ring ID, and thereby avoid using the event ring channel pointer.
This is another step toward no longer assuming an event ring
services a single channel.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Change gsi_channel_trans_map() so it derives the channel used from
the transaction.  Pass the index of the *first* TRE used by the
transaction, and have the called function account for the fact that
the last one used is what's important.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

In gsi_evt_ring_rx_update(), use gsi_event_trans() repeatedly
to find the transaction associated with an event, rather than
assuming consecutive events are associated with the same channel.
This removes the only caller of gsi_trans_pool_next(), so get rid
of it.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Rasmus Villemoes says:

====================
dt-bindings: dp83867: add binding for io_impedance_ctrl nvmem cell

We have a board where measurements indicate that the current three
options - leaving IO_IMPEDANCE_CTRL at the reset value (which is
factory calibrated to a value corresponding to approximately 50 ohms)
or using one of the two boolean properties to set it to the min/max
value - are too coarse.

This series adds a device tree binding for an nvmem cell which can be
populated during production with a suitable value calibrated for each
board, and corresponding support in the driver. The second patch adds
a trivial phy wrapper for dev_err_probe(), used in the third.
====================

Link: https://lore.kernel.org/r/20220614084612.325229-1-linux@rasmusvillemoes.dkSigned-off-by: Jakub Kicinski <kuba@kernel.org>

We have a board where measurements indicate that the current three
options - leaving IO_IMPEDANCE_CTRL at the (factory calibrated) reset
value or using one of the two boolean properties to set it to the
min/max value - are too coarse.

Implement support for the newly added binding allowing device tree to
specify an nvmem cell containing an appropriate value for this
specific board.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The dev_err_probe() function is quite useful to avoid boilerplate
related to -EPROBE_DEFER handling. Add a phydev_err_probe() helper to
simplify making use of that from phy drivers which otherwise use the
phydev_* helpers.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

We have a board where measurements indicate that the current three
options - leaving IO_IMPEDANCE_CTRL at the reset value (which is
factory calibrated to a value corresponding to approximately 50 ohms)
or using one of the two boolean properties to set it to the min/max
value - are too coarse.

There is no fixed mapping from register values to values in the range
35-70 ohms; it varies from chip to chip, and even that target range is
approximate. So add a DT binding for an nvmem cell which can be
populated during production with a value suitable for each specific
board.
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

No conflicts.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pull networking fixes from Jakub Kicinski:
 "Mostly driver fixes.

  Current release - regressions:

   - Revert "net: Add a second bind table hashed by port and address",
     needs more work

   - amd-xgbe: use platform_irq_count(), static setup of IRQ resources
     had been removed from DT core

   - dts: at91: ksz9477_evb: add phy-mode to fix port/phy validation

  Current release - new code bugs:

   - hns3: modify the ring param print info

  Previous releases - always broken:

   - axienet: make the 64b addressable DMA depends on 64b architectures

   - iavf: fix issue with MAC address of VF shown as zero

   - ice: fix PTP TX timestamp offset calculation

   - usb: ax88179_178a needs FLAG_SEND_ZLP

  Misc:

   - document some net.sctp.* sysctls"

* tag 'net-5.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (31 commits)
  net: axienet: add missing error return code in axienet_probe()
  Revert "net: Add a second bind table hashed by port and address"
  net: ax25: Fix deadlock caused by skb_recv_datagram in ax25_recvmsg
  net: usb: ax88179_178a needs FLAG_SEND_ZLP
  MAINTAINERS: add include/dt-bindings/net to NETWORKING DRIVERS
  ARM: dts: at91: ksz9477_evb: fix port/phy validation
  net: bgmac: Fix an erroneous kfree() in bgmac_remove()
  ice: Fix memory corruption in VF driver
  ice: Fix queue config fail handling
  ice: Sync VLAN filtering features for DVM
  ice: Fix PTP TX timestamp offset calculation
  mlxsw: spectrum_cnt: Reorder counter pools
  docs: networking: phy: Fix a typo
  amd-xgbe: Use platform_irq_count()
  octeontx2-vf: Add support for adaptive interrupt coalescing
  xilinx:  Fix build on x86.
  net: axienet: Use iowrite64 to write all 64b descriptor pointers
  net: axienet: make the 64b addresable DMA depends on 64b archectures
  net: hns3: fix tm port shapping of fibre port is incorrect after driver initialization
  net: hns3: fix PF rss size initialization bug
  ...

It should return error code in error path in axienet_probe().

Fixes: 00be43a7 ("net: axienet: make the 64b addresable DMA depends on 64b archectures")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20220616062917.3601-1-yangyingliang@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

This reverts:

commit d5a42de8 ("net: Add a second bind table hashed by port and address")
commit 538aaf9b ("selftests: Add test for timing a bind request to a port with a populated bhash entry")
Link: https://lore.kernel.org/netdev/20220520001834.2247810-1-kuba@kernel.org/

There are a few things that need to be fixed here:
* Updating bhash2 in cases where the socket's rcv saddr changes
* Adding bhash2 hashbucket locks

Links to syzbot reports:
https://lore.kernel.org/netdev/00000000000022208805e0df247a@google.com/
https://lore.kernel.org/netdev/0000000000003f33bc05dfaf44fe@google.com/

Fixes: d5a42de8 ("net: Add a second bind table hashed by port and address")
Reported-by: syzbot+015d756bbd1f8b5c8f09@syzkaller.appspotmail.com
Reported-by: syzbot+98fd2d1422063b0f8c44@syzkaller.appspotmail.com
Reported-by: syzbot+0a847a982613c6438fba@syzkaller.appspotmail.com
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Link: https://lore.kernel.org/r/20220615193213.2419568-1-joannelkoong@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Haiyang Zhang says:

====================
net: mana: Add PF and XDP_REDIRECT support

The patch set adds PF and XDP_REDIRECT support.
====================

Link: https://lore.kernel.org/r/1655238535-19257-1-git-send-email-haiyangz@microsoft.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Add a handler of the XDP_REDIRECT return code from a XDP program. The
packets will be flushed at the end of each RX/CQ NAPI poll cycle.
ndo_xdp_xmit() is implemented by sharing the code in mana_xdp_tx().
Ethtool per queue counters are added for XDP redirect and xmit operations.
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

This minimal PF driver runs on bare metal.
Currently Ethernet TX/RX works. SR-IOV management is not supported yet.
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Co-developed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Some bootloader may set the force speed regs even if the actual
interface should use autonegotiation between PCS and PHY.
This cause the complete malfuction of the interface.

To fix this correctly reset the force speed regs if a fixed-link is not
defined in the DTS. With a fixed-link node correctly configure the
forced speed regs to handle any misconfiguration by the bootloader.
Reported-by: Mark Mentovai <mark@moxienet.com>
Co-developed-by: Mark Mentovai <mark@moxienet.com>
Signed-off-by: Mark Mentovai <mark@moxienet.com>
Signed-off-by: Christian 'Ansuel' Marangi <ansuelsmth@gmail.com>
Link: https://lore.kernel.org/r/20220614112228.1998-2-ansuelsmth@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

The different gmacid require different configuration based on the soc
and on the gmac id. Add these missing configuration taken from the
original driver.
Signed-off-by: Christian 'Ansuel' Marangi <ansuelsmth@gmail.com>
Link: https://lore.kernel.org/r/20220614112228.1998-1-ansuelsmth@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

This patch adds use of KBUILD_MODNAME as defined by the build system,
replacing the definition and use of a custom-defined name.
Signed-off-by: David Thompson <davthompson@nvidia.com>
Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
Link: https://lore.kernel.org/r/20220614212602.28061-1-davthompson@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Pull hardening fixes from Kees Cook:

 - Correctly handle vm_map areas in hardened usercopy (Matthew Wilcox)

 - Adjust CFI RCU usage to avoid boot splats with cpuidle (Sami Tolvanen)

* tag 'hardening-v5.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  usercopy: Make usercopy resilient against ridiculously large copies
  usercopy: Cast pointer to an integer once
  usercopy: Handle vm_map_ram() areas
  cfi: Fix __cfi_slowpath_diag RCU usage with cpuidle

Merge tag 'tpmdd-next-v5.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd

Pull tpm fixes from Jarkko Sakkinen:
 "Two fixes for this merge window"

* tag 'tpmdd-next-v5.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd:
  certs: fix and refactor CONFIG_SYSTEM_BLACKLIST_HASH_LIST build
  certs/blacklist_hashes.c: fix const confusion in certs blacklist

Commit addf4663 ("certs: Check that builtin blacklist hashes are
valid") was applied 8 months after the submission.

In the meantime, the base code had been removed by commit b8c96a6b
("certs: simplify $(srctree)/ handling and remove config_filename
macro").

Fix the Makefile.

Create a local copy of $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST). It is
included from certs/blacklist_hashes.c and also works as a timestamp.

Send error messages from check-blacklist-hashes.awk to stderr instead
of stdout.

Fixes: addf4663 ("certs: Check that builtin blacklist hashes are valid")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Mickaël Salaün <mic@linux.microsoft.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

This file fails to compile as follows:

  CC      certs/blacklist_hashes.o
certs/blacklist_hashes.c:4:1: error: ignoring attribute ‘section (".init.data")’ because it conflicts with previous ‘section (".init.rodata")’ [-Werror=attributes]
    4 | const char __initdata *const blacklist_hashes[] = {
      | ^~~~~
In file included from certs/blacklist_hashes.c:2:
certs/blacklist.h:5:38: note: previous declaration here
    5 | extern const char __initconst *const blacklist_hashes[];
      |                                      ^~~~~~~~~~~~~~~~

Apply the same fix as commit 2be04df5 ("certs/blacklist_nohashes.c:
fix const confusion in certs blacklist").

Fixes: 734114f8 ("KEYS: Add a system blacklist keyring")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Mickaël Salaün <mic@linux.microsoft.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

Pull vfs idmapping fix from Christian Brauner:
 "This fixes an issue where we fail to change the group of a file when
  the caller owns the file and is a member of the group to change to.

  This is only relevant on idmapped mounts.

  There's a detailed description in the commit message and regression
  tests have been added to xfstests"

* tag 'fs.fixes.v5.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  fs: account for group membership

Allow mdb entries to be forwarded to CPU and be switched at the same
time. Only remove entry when no port and the CPU isn't part of the group
anymore.
Signed-off-by: Casper Andersson <casper.casan@gmail.com>
Acked-by: Steen Hegelund <Steen.Hegelund@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The skb_recv_datagram() in ax25_recvmsg() will hold lock_sock
and block until it receives a packet from the remote. If the client
doesn`t connect to server and calls read() directly, it will not
receive any packets forever. As a result, the deadlock will happen.

The fail log caused by deadlock is shown below:

[  369.606973] INFO: task ax25_deadlock:157 blocked for more than 245 seconds.
[  369.608919] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  369.613058] Call Trace:
[  369.613315]  <TASK>
[  369.614072]  __schedule+0x2f9/0xb20
[  369.615029]  schedule+0x49/0xb0
[  369.615734]  __lock_sock+0x92/0x100
[  369.616763]  ? destroy_sched_domains_rcu+0x20/0x20
[  369.617941]  lock_sock_nested+0x6e/0x70
[  369.618809]  ax25_bind+0xaa/0x210
[  369.619736]  __sys_bind+0xca/0xf0
[  369.620039]  ? do_futex+0xae/0x1b0
[  369.620387]  ? __x64_sys_futex+0x7c/0x1c0
[  369.620601]  ? fpregs_assert_state_consistent+0x19/0x40
[  369.620613]  __x64_sys_bind+0x11/0x20
[  369.621791]  do_syscall_64+0x3b/0x90
[  369.622423]  entry_SYSCALL_64_after_hwframe+0x46/0xb0
[  369.623319] RIP: 0033:0x7f43c8aa8af7
[  369.624301] RSP: 002b:00007f43c8197ef8 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
[  369.625756] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f43c8aa8af7
[  369.626724] RDX: 0000000000000010 RSI: 000055768e2021d0 RDI: 0000000000000005
[  369.628569] RBP: 00007f43c8197f00 R08: 0000000000000011 R09: 00007f43c8198700
[  369.630208] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff845e6afe
[  369.632240] R13: 00007fff845e6aff R14: 00007f43c8197fc0 R15: 00007f43c8198700

This patch replaces skb_recv_datagram() with an open-coded variant of it
releasing the socket lock before the __skb_wait_for_more_packets() call
and re-acquiring it after such call in order that other functions that
need socket lock could be executed.

what's more, the socket lock will be released only when recvmsg() will
block and that should produce nicer overall behavior.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Suggested-by: Thomas Osterried <thomas@osterried.de>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reported-by: Thomas Habets <thomas@@habets.se>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>