Universal Serial Ports (USP) can be used as PCM, UART, SPI,
I2S etc. this makes the USP work as UART. the basic work
flow is same with UART controller, the main difference will
be offset of registers and bits.

this patch makes the old sirfsoc uart driver support both
sirf UART and USP-based UART by making their differences
become private data.
Signed-off-by: NQipan Li <Qipan.Li@csr.com>
Signed-off-by: NBarry Song <Baohua.Song@csr.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

the marco and coming new CSR multiple SoCs have SET/CLR pair for
INTEN registers to avoid some read-modify-write.

this patch adds support for this and make the driver support current
up and coming mp SoCs.
Signed-off-by: NBarry Song <Baohua.Song@csr.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

devicetrees may have the linux,stdout-path property to specify the
console. This patch adds support to the i.MX serial driver for this.
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

devicetrees may have a linux,stdout-path property in the chosen
node describing the console device. This adds a helper function
to match a device against this property so a driver can call
add_preferred_console for a matching device.
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>
Acked-by: NRob Herring <rob.herring@calxeda.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use devm_* functions in order to simplify cleanup
paths.
Signed-off-by: NGabor Juhos <juhosg@openwrt.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Lockdep reports a circular lock dependency between
atomic_read_lock and termios_rwsem [1]. However, a lock
order deadlock is not possible since CPU1 only holds a
read lock which cannot prevent CPU0 from also acquiring
a read lock on the same r/w semaphore.

Unfortunately, lockdep cannot currently distinguish whether
the locks are read or write for any particular lock graph,
merely that the locks _were_ previously read and/or write.

Until lockdep is fixed, re-order atomic_read_lock so
termios_rwsem can be dropped and reacquired without
triggering lockdep.

Patch based on original posted here https://lkml.org/lkml/2013/8/1/510
by Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

[1] Initial lockdep report from Artem Savkov <artem.savkov@gmail.com>

 ======================================================
 [ INFO: possible circular locking dependency detected ]
 3.11.0-rc3-next-20130730+ #140 Tainted: G        W
 -------------------------------------------------------
 bash/1198 is trying to acquire lock:
  (&tty->termios_rwsem){++++..}, at: [<ffffffff816aa3bb>] n_tty_read+0x49b/0x660

 but task is already holding lock:
  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff816aa0f0>] n_tty_read+0x1d0/0x660

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 (&ldata->atomic_read_lock){+.+...}:
        [<ffffffff811111cc>] validate_chain+0x73c/0x850
        [<ffffffff811117e0>] __lock_acquire+0x500/0x5d0
        [<ffffffff81111a29>] lock_acquire+0x179/0x1d0
        [<ffffffff81d34b9c>] mutex_lock_interruptible_nested+0x7c/0x540
        [<ffffffff816aa0f0>] n_tty_read+0x1d0/0x660
        [<ffffffff816a3bb6>] tty_read+0x86/0xf0
        [<ffffffff811f21d3>] vfs_read+0xc3/0x130
        [<ffffffff811f2702>] SyS_read+0x62/0xa0
        [<ffffffff81d45259>] system_call_fastpath+0x16/0x1b

 -> #0 (&tty->termios_rwsem){++++..}:
        [<ffffffff8111064f>] check_prev_add+0x14f/0x590
        [<ffffffff811111cc>] validate_chain+0x73c/0x850
        [<ffffffff811117e0>] __lock_acquire+0x500/0x5d0
        [<ffffffff81111a29>] lock_acquire+0x179/0x1d0
        [<ffffffff81d372c1>] down_read+0x51/0xa0
        [<ffffffff816aa3bb>] n_tty_read+0x49b/0x660
        [<ffffffff816a3bb6>] tty_read+0x86/0xf0
        [<ffffffff811f21d3>] vfs_read+0xc3/0x130
        [<ffffffff811f2702>] SyS_read+0x62/0xa0
        [<ffffffff81d45259>] system_call_fastpath+0x16/0x1b

 other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&ldata->atomic_read_lock);
                                lock(&tty->termios_rwsem);
                                lock(&ldata->atomic_read_lock);
   lock(&tty->termios_rwsem);

  *** DEADLOCK ***

 2 locks held by bash/1198:
  #0:  (&tty->ldisc_sem){.+.+.+}, at: [<ffffffff816ade04>] tty_ldisc_ref_wait+0x24/0x60
  #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff816aa0f0>] n_tty_read+0x1d0/0x660

 stack backtrace:
 CPU: 1 PID: 1198 Comm: bash Tainted: G        W    3.11.0-rc3-next-20130730+ #140
 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
  0000000000000000 ffff880019acdb28 ffffffff81d34074 0000000000000002
  0000000000000000 ffff880019acdb78 ffffffff8110ed75 ffff880019acdb98
  ffff880019fd0000 ffff880019acdb78 ffff880019fd0638 ffff880019fd0670
 Call Trace:
  [<ffffffff81d34074>] dump_stack+0x59/0x7d
  [<ffffffff8110ed75>] print_circular_bug+0x105/0x120
  [<ffffffff8111064f>] check_prev_add+0x14f/0x590
  [<ffffffff81d3ab5f>] ? _raw_spin_unlock_irq+0x4f/0x70
  [<ffffffff811111cc>] validate_chain+0x73c/0x850
  [<ffffffff8110ae0f>] ? trace_hardirqs_off_caller+0x1f/0x190
  [<ffffffff811117e0>] __lock_acquire+0x500/0x5d0
  [<ffffffff81111a29>] lock_acquire+0x179/0x1d0
  [<ffffffff816aa3bb>] ? n_tty_read+0x49b/0x660
  [<ffffffff81d372c1>] down_read+0x51/0xa0
  [<ffffffff816aa3bb>] ? n_tty_read+0x49b/0x660
  [<ffffffff816aa3bb>] n_tty_read+0x49b/0x660
  [<ffffffff810e4130>] ? try_to_wake_up+0x210/0x210
  [<ffffffff816a3bb6>] tty_read+0x86/0xf0
  [<ffffffff811f21d3>] vfs_read+0xc3/0x130
  [<ffffffff811f2702>] SyS_read+0x62/0xa0
  [<ffffffff815e24ee>] ? trace_hardirqs_on_thunk+0x3a/0x3f
  [<ffffffff81d45259>] system_call_fastpath+0x16/0x1b
Reported-by: NArtem Savkov <artem.savkov@gmail.com>
Reported-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

These local symbols are used only in this file.
Fix the following sparse warnings:

drivers/tty/serial/pxa.c:793:17: warning: symbol 'serial_pxa_pops' was not declared. Should it be static?
drivers/tty/serial/pxa.c:971:12: warning: symbol 'serial_pxa_init' was not declared. Should it be static?
drivers/tty/serial/pxa.c:986:13: warning: symbol 'serial_pxa_exit' was not declared. Should it be static?
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This #if-0'd block wouldn't compile, so let's dispose it.
Signed-off-by: NDaniel Mack <zonque@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch guards the console_drivers list to be corrupted. The
for_each_console() macro insist on a strictly forward list ended by NULL:

 con0->next->con1->next->NULL

Without this patch it may happen easily to destroy this list for example by
adding 'earlyprintk' twice, especially on embedded devices where the early
console is often a single static instance.  This will result in the following
list:

 con0->next->con0

This in turn will result in an endless loop in console_unlock() later on by
printing the first __log_buf line endlessly.
Signed-off-by: NAndreas Bießmann <andreas@biessmann.de>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The virtual console has (undocumented) module parameters to set the
colors for italic and underlined text, but the default text color was
hardcoded for some reason.  This made it impossible to change the color
for startup messages, or to set the default for new virtual consoles.
Add a module parameter for that, and document the entire bunch.

Any hacker who thinks that a command prompt on a "black screen with
white font" is not supicious enough can now use the kernel parameter
vt.color=10 to get a nice, evil green.
Signed-off-by: NClemens Ladisch <clemens@ladisch.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add the RTS/CTS property for auart0 which means we enable the
DMA support for it.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The MXS_AUART_DMA_CONFIG is originally used to check if the DT node
is configured with the DMA property.

But now, the MXS_AUART_DMA_CONFIG is set unconditionally in the
serial_mxs_probe_dt(), so the check in the mxs_auart_settermios() is
not necessary anymore. This patch removes this macro.
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The original DMA support works only when RTS/CTS is enabled.
(see the "e8001632 serial: mxs-auart: add the DMA support for mx28")
But after several patches, DMA support has lost this limit.
(see the "bcc20f9e serial: mxs-auart: move to use generic DMA helper")

So an UART without the RTS/CTS lines may also enables the DMA support,
in which case the UART may gets unpredictable results.

This patch adds an optional property for the UART DT node
which indicates the UART has RTS and CTS lines, and it also means you
enable the DMA support for this UART.

This patch also adds a macro MXS_AUART_RTSCTS, and uses it to check
RTS/CTS before we enable the DMA for the UART.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We want the tty fixes in here as well.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull dmaengine fixes from Vinod Koul:
 "Two fixes for slave dmaengine.  The first fixes cyclic dma transfers
  for pl330 and the second one makes us return the correct error code on
  probe"

* 'fixes' of git://git.infradead.org/users/vkoul/slave-dma:
  dma: pl330: Fix cyclic transfers
  pch_dma: fix error return code in pch_dma_probe()

Pull drm fix from Dave Airlie:
 "Just a quick fix that a few people have reported, be nice to have in
  asap"

The drm tree seems to be very confused about 64-bit divides.  Here it
uses a slow 64-by-64 bit divide to divide by a small constant.  Oh well.
Doesn't look performance-critical, just stupid.

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/radeon: fix 64 bit divide in SI spm code

Commit 46a1c2c7 ("vfs: export lseek_execute() to modules") broke the
tmpfs SEEK_DATA/SEEK_HOLE implementation, because vfs_setpos() converts
the carefully prepared -ENXIO to -EINVAL.  Other filesystems avoid it in
error cases: do the same in tmpfs.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Jie Liu <jeff.liu@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull sound fixes from Takashi Iwai:
 "All small regression or small fixes, nothing surprising at this stage.

   - regression fix for intel Mac Mini quirk
   - compress ioctl error fix
   - ASoC fixes for control change notifications, some UI fixes,
     driver-specific fixes (resource leak, build errors, etc)"

* tag 'sound-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Fix missing fixup for Mac Mini with STAC9221
  ASoC: wm0010: Fix resource leak
  ASoC: au1x: Fix build
  ASoC: bf5xx-ac97: Fix compile error with SND_BF5XX_HAVE_COLD_RESET
  ASoC: bfin-ac97: Fix prototype error following AC'97 refactoring
  ALSA: compress: fix the return value for SNDRV_COMPRESS_VERSION
  ASoC: dapm: Fix return value of snd_soc_dapm_put_{volsw,enum_virt}()

Forgot to use the appropriate math64 function.
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

Pull networking fixes from David Miller:

 1) Don't ignore user initiated wireless regulatory settings on cards
    with custom regulatory domains, from Arik Nemtsov.

 2) Fix length check of bluetooth information responses, from Jaganath
    Kanakkassery.

 3) Fix misuse of PTR_ERR in btusb, from Adam Lee.

 4) Handle rfkill properly while iwlwifi devices are offline, from
    Emmanuel Grumbach.

 5) Fix r815x devices DMA'ing to stack buffers, from Hayes Wang.

 6) Kernel info leak in ATM packet scheduler, from Dan Carpenter.

 7) 8139cp doesn't check for DMA mapping errors, from Neil Horman.

 8) Fix bridge multicast code to not snoop when no querier exists,
    otherwise mutlicast traffic is lost.  From Linus Lüssing.

 9) Avoid soft lockups in fib6_run_gc(), from Michal Kubecek.

10) Fix races in automatic address asignment on ipv6, which can result
    in incorrect lifetime assignments.  From Jiri Benc.

11) Cure build bustage when CONFIG_NET_LL_RX_POLL is not set and rename
    it CONFIG_NET_RX_BUSY_POLL to eliminate the last reference to the
    original naming of this feature.  From Cong Wang.

12) Fix crash in TIPC when server socket creation fails, from Ying Xue.

13) macvlan_changelink() silently succeeds when it shouldn't, from
    Michael S Tsirkin.

14) HTB packet scheduler can crash due to sign extension, fix from
    Stephen Hemminger.

15) With the cable unplugged, r8169 prints out a message every 10
    seconds, make it netif_dbg() instead of netif_warn().  From Peter
    Wu.

16) Fix memory leak in rtm_to_ifaddr(), from Daniel Borkmann.

17) sis900 gets spurious TX queue timeouts due to mismanagement of link
    carrier state, from Denis Kirjanov.

18) Validate somaxconn sysctl to make sure it fits inside of a u16.
    From Roman Gushchin.

19) Fix MAC address filtering on qlcnic, from Shahed Shaikh.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (68 commits)
  qlcnic: Fix for flash update failure on 83xx adapter
  qlcnic: Fix link speed and duplex display for 83xx adapter
  qlcnic: Fix link speed display for 82xx adapter
  qlcnic: Fix external loopback test.
  qlcnic: Removed adapter series name from warning messages.
  qlcnic: Free up memory in error path.
  qlcnic: Fix ingress MAC learning
  qlcnic: Fix MAC address filter issue on 82xx adapter
  net: ethernet: davinci_emac: drop IRQF_DISABLED
  netlabel: use domain based selectors when address based selectors are not available
  net: check net.core.somaxconn sysctl values
  sis900: Fix the tx queue timeout issue
  net: rtm_to_ifaddr: free ifa if ifa_cacheinfo processing fails
  r8169: remove "PHY reset until link up" log spam
  net: ethernet: cpsw: drop IRQF_DISABLED
  htb: fix sign extension bug
  macvlan: handle set_promiscuity failures
  macvlan: better mode validation
  tipc: fix oops when creating server socket fails
  net: rename CONFIG_NET_LL_RX_POLL to CONFIG_NET_RX_BUSY_POLL
  ...

Flash update routine was improperly checking register read API return value.
Modify register read API and perform proper error check.
Signed-off-by: NHimanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

o Set link speed and duplex to unknown when link is not up.
Signed-off-by: NRajesh Borundia <rajesh.borundia@qlogic.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

o Do not obtain link speed from register when adapter
  link is down.
Signed-off-by: NRajesh Borundia <rajesh.borundia@qlogic.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Driver was not handling external loopback diagnostic
test request.
Signed-off-by: NShahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NPratik Pujar <pratik.pujar@qlogic.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NHimanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

o Delete MAC address from the adapter's filter table
  if the source MAC address of ingress packet matches.
Signed-off-by: NShahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Driver was passing the address of a pointer instead of
the pointer itself.
Signed-off-by: NShahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

IRQF_DISABLED is a no-op by now and should be removed.
Signed-off-by: NMugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pull nfsd bugfixes from Bruce Fields:
 "Most of this is due to a screwup on my part -- some gss-proxy crashes
  got fixed before the merge window but somehow never made it out of a
  temporary git repo on my laptop...."

* 'for-3.11' of git://linux-nfs.org/~bfields/linux:
  svcrpc: set cr_gss_mech from gss-proxy as well as legacy upcall
  svcrpc: fix kfree oops in gss-proxy code
  svcrpc: fix gss-proxy xdr decoding oops
  svcrpc: fix gss_rpc_upcall create error
  NFSD/sunrpc: avoid deadlock on TCP connection due to memory pressure.

Pull hwmon fix from Guenter Roeck:
 "Fix chip initialization/configuration in MAX6697 driver"

* tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (max6697) fix MAX6581 ideality

Pull arm fixes fixes from Russell King:
 "This fixes a couple of problems with commit 48be69a0 ("ARM: move
  signal handlers into a vdso-like page"), one of which was originally
  discovered via my testing originally, but the fix for it was never
  actually committed.

  The other shows up on noMMU builds, and such platforms are extremely
  rare and as such are not part of my nightly testing"

* 'fixes' of git://git.linaro.org/people/rmk/linux-arm:
  ARM: fix nommu builds with 48be69a0 (ARM: move signal handlers into a vdso-like page)
  ARM: fix a cockup in 48be69a0 (ARM: move signal handlers into a vdso-like page)

Without this patch, the values for ideality (register 0x4b) and ideality
selection mask (register 0x4c) are inverted.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Cc: stable@vger.kernel.org # 3.9+
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>

Olof reports that noMMU builds error out with:

arch/arm/kernel/signal.c: In function 'setup_return':
arch/arm/kernel/signal.c:413:25: error: 'mm_context_t' has no member named 'sigpage'

This shows one of the evilnesses of IS_ENABLED().  Get rid of it here
and replace it with #ifdef's - and as no noMMU platform can make use
of sigpage, depend on CONIFG_MMU not CONFIG_ARM_MPU.
Reported-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Unfortunately, I never committed the fix to a nasty oops which can
occur as a result of that commit:

------------[ cut here ]------------
kernel BUG at /home/olof/work/batch/include/linux/mm.h:414!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 490 Comm: killall5 Not tainted 3.11.0-rc3-00288-gabe03080 #53
task: e90acac0 ti: e9be8000 task.ti: e9be8000
PC is at special_mapping_fault+0xa4/0xc4
LR is at __do_fault+0x68/0x48c

This doesn't show up unless you do quite a bit of testing; a simple
boot test does not do this, so all my nightly tests were passing fine.

The reason for this is that install_special_mapping() expects the
page array to stick around, and as this was only inserting one page
which was stored on the kernel stack, that's why this was blowing up.
Reported-by: NOlof Johansson <olof@lixom.net>
Tested-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch fixes a below warning reported by kbuild test robot.

drivers/tty/serial/st-asc.c:727:28: warning: 'asc_match' defined but
 not used [-Wunused-variable]

The code used in DT case is now ifdefed under CONFIG_OF to fix this
warning.
Signed-off-by: NSrinivas Kandagatla <srinivas.kandagatla@st.com>
Reported-by: NKbuild Test Robot <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

NetLabel has the ability to selectively assign network security labels
to outbound traffic based on either the LSM's "domain" (different for
each LSM), the network destination, or a combination of both.  Depending
on the type of traffic, local or forwarded, and the type of traffic
selector, domain or address based, different hooks are used to label the
traffic; the goal being minimal overhead.

Unfortunately, there is a bug such that a system using NetLabel domain
based traffic selectors does not correctly label outbound local traffic
that is not assigned to a socket.  The issue is that in these cases
the associated NetLabel hook only looks at the address based selectors
and not the domain based selectors.  This patch corrects this by
checking both the domain and address based selectors so that the correct
labeling is applied, regardless of the configuration type.

In order to acomplish this fix, this patch also simplifies some of the
NetLabel domainhash structures to use a more common outbound traffic
mapping type: struct netlbl_dommap_def.  This simplifies some of the code
in this patch and paves the way for further simplifications in the
future.
Signed-off-by: NPaul Moore <pmoore@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It's possible to assign an invalid value to the net.core.somaxconn
sysctl variable, because there is no checks at all.

The sk_max_ack_backlog field of the sock structure is defined as
unsigned short. Therefore, the backlog argument in inet_listen()
shouldn't exceed USHRT_MAX. The backlog argument in the listen() syscall
is truncated to the somaxconn value. So, the somaxconn value shouldn't
exceed 65535 (USHRT_MAX).
Also, negative values of somaxconn are meaningless.

before:
$ sysctl -w net.core.somaxconn=256
net.core.somaxconn = 256
$ sysctl -w net.core.somaxconn=65536
net.core.somaxconn = 65536
$ sysctl -w net.core.somaxconn=-100
net.core.somaxconn = -100

after:
$ sysctl -w net.core.somaxconn=256
net.core.somaxconn = 256
$ sysctl -w net.core.somaxconn=65536
error: "Invalid argument" setting key "net.core.somaxconn"
$ sysctl -w net.core.somaxconn=-100
error: "Invalid argument" setting key "net.core.somaxconn"

Based on a prior patch from Changli Gao.
Signed-off-by: NRoman Gushchin <klamm@yandex-team.ru>
Reported-by: NChangli Gao <xiaosuo@gmail.com>
Suggested-by: NEric Dumazet <edumazet@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>