Don't expose skbs to in-kernel users, such as the AFS filesystem, but
instead provide a notification hook the indicates that a call needs
attention and another that indicates that there's a new call to be
collected.

This makes the following possibilities more achievable:

 (1) Call refcounting can be made simpler if skbs don't hold refs to calls.

 (2) skbs referring to non-data events will be able to be freed much sooner
     rather than being queued for AFS to pick up as rxrpc_kernel_recv_data
     will be able to consult the call state.

 (3) We can shortcut the receive phase when a call is remotely aborted
     because we don't have to go through all the packets to get to the one
     cancelling the operation.

 (4) It makes it easier to do encryption/decryption directly between AFS's
     buffers and sk_buffs.

 (5) Encryption/decryption can more easily be done in the AFS's thread
     contexts - usually that of the userspace process that issued a syscall
     - rather than in one of rxrpc's background threads on a workqueue.

 (6) AFS will be able to wait synchronously on a call inside AF_RXRPC.

To make this work, the following interface function has been added:

     int rxrpc_kernel_recv_data(
		struct socket *sock, struct rxrpc_call *call,
		void *buffer, size_t bufsize, size_t *_offset,
		bool want_more, u32 *_abort_code);

This is the recvmsg equivalent.  It allows the caller to find out about the
state of a specific call and to transfer received data into a buffer
piecemeal.

afs_extract_data() and rxrpc_kernel_recv_data() now do all the extraction
logic between them.  They don't wait synchronously yet because the socket
lock needs to be dealt with.

Five interface functions have been removed:

	rxrpc_kernel_is_data_last()
    	rxrpc_kernel_get_abort_code()
    	rxrpc_kernel_get_error_number()
    	rxrpc_kernel_free_skb()
    	rxrpc_kernel_data_consumed()

As a temporary hack, sk_buffs going to an in-kernel call are queued on the
rxrpc_call struct (->knlrecv_queue) rather than being handed over to the
in-kernel user.  To process the queue internally, a temporary function,
temp_deliver_data() has been added.  This will be replaced with common code
between the rxrpc_recvmsg() path and the kernel_rxrpc_recv_data() path in a
future patch.
Signed-off-by: David Howells <dhowells@redhat.com>

Pass struct socket * to more rxrpc kernel interface functions.  They should
be starting from this rather than the socket pointer in the rxrpc_call
struct if they need to access the socket.

I have left:

	rxrpc_kernel_is_data_last()
	rxrpc_kernel_get_abort_code()
	rxrpc_kernel_get_error_number()
	rxrpc_kernel_free_skb()
	rxrpc_kernel_data_consumed()

unmodified as they're all about to be removed (and, in any case, don't
touch the socket).
Signed-off-by: David Howells <dhowells@redhat.com>

Use call->peer rather than call->conn->params.peer as call->conn may become
NULL.
Signed-off-by: David Howells <dhowells@redhat.com>

Provide a function so that kernel users, such as AFS, can ask for the peer
address of a call:

   void rxrpc_kernel_get_peer(struct rxrpc_call *call,
			      struct sockaddr_rxrpc *_srx);

In the future the kernel service won't get sk_buffs to look inside.
Further, this allows us to hide any canonicalisation inside AF_RXRPC for
when IPv6 support is added.

Also propagate this through to afs_find_server() and issue a warning if we
can't handle the address family yet.
Signed-off-by: David Howells <dhowells@redhat.com>

We should #include linux/random.h to use get_random().
Signed-off-by: David Howells <dhowells@redhat.com>

Remove one #ifndef'd-out variable and a couple of excessive blank lines.
Signed-off-by: David Howells <dhowells@redhat.com>

Add a trace event for debuging rxrpc_call struct usage.
Signed-off-by: David Howells <dhowells@redhat.com>

Condense the terminal states of a call state machine to a single state,
plus a separate completion type value.  The value is then set, along with
error and abort code values, only when the call is transitioned to the
completion state.

Helpers are provided to simplify this.
Signed-off-by: David Howells <dhowells@redhat.com>

The call pointer in a channel on a connection will be NULL if there's no
active call on that channel.  rxrpc_abort_calls() needs to check for this
before trying to take the call's state_lock.
Signed-off-by: David Howells <dhowells@redhat.com>

Jeff Kirsher says:

====================
100GbE Intel Wired LAN Driver Updates 2016-08-29

This series contains updates to fm10k only.

Jake provides all the changes in this series starting with fixes an issue
where VF devices may fail during an unbind/bind and we will never zero
the reference counter for the pci_dev structure.  Updated the hot path
to use SW counters instead of checking for hardware Tx pending for
possible transmit hangs, which will improve performance.  Fixed the NAPI
budget accounting so that fm10k_poll will return actual work done,
capped at (budget - 1) instead of returning 0.  Added a check to ensure
that the device is in the normal IO state before continuing to probe,
which allows us to give a more descriptive message of what is wrong
in the case of uncorrectable AER error.  In preparation for adding Geneve
Rx offload support, refactored the current VXLAN offload flow to be a bit
more generic.  Added support for receive offloads on one Geneve tunnel.
Ensure that other bits in the RXQCTL register do not get cleared, to
make sure that bits related to queue ownership are maintained.  Fixed
an issue in queue ownership assignment which casued a race condition
between the PF and the VF such that potentially a VF could cause FUM
fault errors due to normal PF/VF driver behavior.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

All three conflicts were cases of simple overlapping
changes.
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge tag 'hwmon-for-linus-v4.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull hwmon fix from Guenter Roeck:
 "Add missing sysfs attribute group terminator to it87 driver"

* tag 'hwmon-for-linus-v4.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (it87) Add missing sysfs attribute group terminator

Pull ext4 fixes from Ted Ts'o:
 "Fix bugs that could cause kernel deadlocks or file system corruption
  while moving xattrs to expand the extended inode.

  Also add some sanity checks to the block group descriptors to make
  sure we don't end up overwriting the superblock"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: avoid deadlock when expanding inode size
  ext4: properly align shifted xattrs when expanding inodes
  ext4: fix xattr shifting when expanding inodes part 2
  ext4: fix xattr shifting when expanding inodes
  ext4: validate that metadata blocks do not overlap superblock
  ext4: reserve xattr index for the Hurd

Pull networking fixes from David Miller:

 1) Segregate namespaces properly in conntrack dumps, from Liping Zhang.

 2) tcp listener refcount fix in netfilter tproxy, from Eric Dumazet.

 3) Fix timeouts in qed driver due to xmit_more, from Yuval Mintz.

 4) Fix use-after-free in tcp_xmit_retransmit_queue().

 5) Userspace header fixups (use of __u32, missing includes, etc.) from
    Mikko Rapeli.

 6) Further refinements to fragmentation wrt gso and tunnels, from
    Shmulik Ladkani.

 7) Trigger poll correctly for zero length UDP packets, from Eric
    Dumazet.

 8) TCP window scaling fix, also from Eric Dumazet.

 9) SLAB_DESTROY_BY_RCU is not relevant any more for UDP sockets.

10) Module refcount leak in qdisc_create_dflt(), from Eric Dumazet.

11) Fix deadlock in cp_rx_poll() of 8139cp driver, from Gao Feng.

12) Memory leak in rhashtable's alloc_bucket_locks(), from Eric Dumazet.

13) Add new device ID to alx driver, from Owen Lin.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (83 commits)
  Add Killer E2500 device ID in alx driver.
  net: smc91x: fix SMC accesses
  Documentation: networking: dsa: Remove platform device TODO
  net/mlx5: Increase number of ethtool steering priorities
  net/mlx5: Add error prints when validate ETS failed
  net/mlx5e: Fix memory leak if refreshing TIRs fails
  net/mlx5e: Add ethtool counter for TX xmit_more
  net/mlx5e: Fix ethtool -g/G rx ring parameter report with striding RQ
  net/mlx5e: Don't wait for SQ completions on close
  net/mlx5e: Don't post fragmented MPWQE when RQ is disabled
  net/mlx5e: Don't wait for RQ completions on close
  net/mlx5e: Limit UMR length to the device's limitation
  rhashtable: fix a memory leak in alloc_bucket_locks()
  sfc: fix potential stack corruption from running past stat bitmask
  team: loadbalance: push lacpdus to exact delivery
  net: hns: dereference ppe_cb->ppe_common_cb if it is non-null
  8139cp: Fix one possible deadloop in cp_rx_poll
  i40e: Change some init flow for the client
  Revert "phy: IRQ cannot be shared"
  net: dsa: bcm_sf2: Fix race condition while unmasking interrupts
  ...

Merge tag 'platform-drivers-x86-v4.8-4' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

Pull x86 platform driver fixes from Darren Hart:
 "Remove module related code from two drivers that are only configurable
  as built-in: intel_pmic_gpio and platform/olpc"

* tag 'platform-drivers-x86-v4.8-4' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
  intel_pmic_gpio: Make explicitly non-modular
  platform/olpc: Make ec explicitly non-modular

Pull powerpc fixes from Ben Herrenschmidt:
 "This was meant to be sent early last week, but I has a change pending
  on one of the fixes and other things made me forget all about.  Ugh.

  We have some misc fixes for powerpc 4.8.  Some trivial bits and some
  regressions, and a trivial cleanup or two that I saw no point in
  letting rot in patchwork"

* tag 'powerpc-4.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc: signals: Discard transaction state from signal frames
  powerpc/powernv : Drop reference added by kset_find_obj()
  powerpc/tm: do not use r13 for tabort_syscall
  powerpc: move hmi.c to arch/powerpc/kvm/
  powerpc: sysdev: cpm: fix gpio save_regs functions
  powerpc/pseries: PACA save area fix for MCE vs MCE
  powerpc/pseries: PACA save area fix for general exception vs MCE
  powerpc/prom: Fix sub-processor option passed to ibm, client-architecture-support
  powerpc, hotplug: Avoid to touch non-existent cpumasks.
  powerpc: migrate exception table users off module.h and onto extable.h
  powerpc/powernv/pci: fix iterator signedness
  powerpc/pseries: use pci_host_bridge.release_fn() to kfree(phb)
  cxl: use pcibios_free_controller_deferred() when removing vPHBs
  powerpc: mpc8349emitx: Delete unnecessary assignment for the field "owner"
  powerpc/512x: Delete unnecessary assignment for the field "owner"
  drivers/macintosh: Delete owner assignment
  powerpc: cputhreads: Add missing include file

Attribute array it87_attributes_in lacks its NULL terminator,
causing random behavior when operating on the attribute group.

Fixes: 52929715 ("hwmon: (it87) Use is_visible for voltage sensors")
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: stable@vger.kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

When the PF assigns a new MAC address to a VF it uses the base address
registers to store the MAC address. This allows a VF which loads after
this setup the ability to get the initial address without having to wait
for a mailbox message. Unfortunately to do this, the PF must take queue
ownership away from the VF, which can cause fault errors when there is
already an active VF driver.

This queue ownership assignment causes race condition between the PF and
the VF such that potentially a VF can cause FUM fault errors due to
normal PF/VF driver behavior.

It is not safe to simply allow the PF to write the base address
registers without taking queue ownership back as the PF must also
disable the queues, and this would impact active VF use. The current
code is safe because the queue ownership will prevent the VF from
actually writing but does trigger the FUM fault.

We can do better by simply avoiding the register write process when
a mailbox message suffices. If the message can be sent over the mailbox,
then we will not perform the queue ownership assignment and we won't
update the base address to be the same as the MAC address.

We do still have to write the TXQCTL registers in order to update the
VID of the queue. This is necessary because the TXQCTL register is
read-only from the VF, and thus the VF cannot do this for itself. This
register does not need to wait for the Tx queue to be disabled and is
safe for the PF to write during normal VF operation, so we move this
write to the top of the function above the mailbox message. Without
this, the TXQCTL register would be misconfigured and cause the VF to Tx
hang.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Ensure that other bits in the RXQCTL register do not get cleared. This
ensures that bits related to queue ownership are maintained.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Similar to how we handle VXLAN offload, enable support for a single
Geneve tunnel.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

In preparation for adding Geneve Rx offload support, refactor the
current VXLAN offload flow to be a bit more generic so that it will be
easier to add the new Geneve code. The fm10k hardware supports one VXLAN
and one Geneve tunnel, so we will eventually treat the VXLAN and Geneve
tunnels identically. To this end, factor out the code that handles the
current list so that we can use the generic flow for both tunnels in the
next patch.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

In the event of a surprise remove, we expect the driver to go down,
which includes calling .stop_hw(). However, this function will return an
error because the queues won't appear to cleanly disable. Prevent this
and avoid the unnecessary checks by just returning when
FM10K_REMOVED(hw->hw_addr) is true.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

In the event of an uncorrectable AER error occurring when the driver has
not loaded, the recovery routines are not done. This is done because
future loads of the driver may not be aware of the IO state and may not
be able to recover at all. In this case, when we next load the driver it
fails due to what appears to be a surprise remove event. Instead, add
a check to ensure that the device is in the normal IO state before
continuing to probe. This allows us to give a more descriptive message
of what is wrong.

Without this change, the driver will attempt to probe up to our first
call of .reset_hw() which will be unable to read registers and act as if
a surprise remove event occurred.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

When fm10k_poll fully cleans rings it returns 0. This is incorrect as it
messes up the budget accounting in the core NAPI code. Fix this by
returning actual work done, capped at budget - 1 since the core doesn't
expect a return of the full budget when the driver modifies the NAPI
status.

Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Venkatesh Srinivas <venkateshs@google.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

While technically not needed, as all our uses of ACCESS_ONCE are scalar
types, we already use READ_ONCE in a few places, and for code
readability we can swap all the uses of the older ACCESS_ONCE into
READ_ONCE.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

The function is only used in fm10k_ethtool.c, so make it static.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

A previous patch added support to check for hardware Tx pending in the
fm10k_down routine. This support was intended to ensure that we
accurately check what the hardware state is. However, checking for Tx
hangs in this manor during the hotpath results in a large performance
hit. Avoid this by making the hotpath check use the SW counters instead.

Fixes: a0f53cf49cb0 ("fm10k: use actual hardware registers when checking for pending Tx", 2016-06-08)
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

A previous patch removed the pci_disable_device() call in
.io_error_detected. This call corresponded to a pci_enable_device_mem()
call within .io_slot_reset handler. Change the call here to
a pci_reenable_device() so that it does not increment and leak the
enable_cnt reference count for the device. Without this change, VF
devices may fail during an unbind/bind, and we'll never zero the
reference counter for the pci_dev structure.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

The Kconfig entry controlling compilation of this code is:

drivers/platform/x86/Kconfig:config GPIO_INTEL_PMIC
drivers/platform/x86/Kconfig:   bool "Intel PMIC GPIO support"

...meaning that it currently is not being built as a module by anyone.

Lets remove the couple traces of modular infrastructure use, so that
when reading the driver there is no doubt it is builtin-only.

We delete the MODULE_LICENSE tag etc. since all that information
was (or is now) contained at the top of the file in the comments.

We don't replace module.h with init.h since the file already has that.

Cc: Alek Du <alek.du@intel.com>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

The Kconfig entry controlling compilation of this code is:

arch/x86/Kconfig:config OLPC
arch/x86/Kconfig:       bool "One Laptop Per Child support"

...meaning that it currently is not being built as a module by anyone.

Lets remove the couple traces of modular infrastructure use, so that
when reading the driver there is no doubt it is builtin-only.

We delete the MODULE_LICENSE tag etc. since all that information
was (or is now) contained at the top of the file in the comments.

Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

The addition of VLAN support caused a possible use of uninitialized
data if we encounter a zero TCA_FLOWER_KEY_ETH_TYPE key, as pointed
out by "gcc -Wmaybe-uninitialized":

net/sched/cls_flower.c: In function 'fl_change':
net/sched/cls_flower.c:366:22: error: 'ethertype' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This changes the code to only set the ethertype field if it
was nonzero, as before the patch.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 9399ae9a ("net_sched: flower: Add vlan support")
Cc: Hadar Hen Zion <hadarh@mellanox.com>
Cc: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The newly added reset logic uses helper functions for the MMIO that
may fail. However, when the read operation fails, we end up writing
back uninitialized data to the register, as gcc warns:

drivers/net/ethernet/apm/xgene/xgene_enet_xgmac.c: In function 'xgene_enet_link_state':
drivers/net/ethernet/apm/xgene/xgene_enet_xgmac.c:213:2: error: 'data' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/net/ethernet/apm/xgene/xgene_enet_xgmac.c:209:6: note: 'data' was declared here
  u32 data;

We already print a warning to the console log if that happens,
the best alternative that I can see is skip the rest of the reset
sequence if the register value cannot be read: Most likely the
write would fail as well, and if it succeeded, worse things could
happen.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 3eb7cb9d ("drivers: net: xgene: XFI PCS reset when link is down")
Cc: Fushen Chen <fchen@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch enhances ethtool link mode bitmap to include
missing interface modes for 1G/10G speeds

Changes:
1000baseX is the mode introduced to cover all 1G Fiber cases.
All modes under 1000BaseX i.e. 1000BASE-SX, 1000BASE-LX, 1000BASE-LX10
and 1000BASE-BX10 are not explicitly defined at this moment.
10G CR,SR,LR and ER link modes are included for 10G speed..

Issue:
ethtool on  1G/10G SFP port reports Base-T
as this port supports 1000baseX,10G CR, SR and LR modes.

root@tor-02$ ethtool swp1
Settings for swp1:
        Supported ports: [ FIBRE ]
        Supported link modes:   1000baseT/Full
                                10000baseT/Full
        Supported pause frame use: Symmetric Receive-only
        Supports auto-negotiation: Yes
        Advertised link modes:  1000baseT/Full
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Speed: 10000Mb/s
        Duplex: Full
        Port: FIBRE
        PHYAD: 0
        Transceiver: external
        Auto-negotiation: off
        Current message level: 0x00000000 (0)

        Link detected: yes

After fix:
root@tor-02$ ethtool swp1
Settings for swp1:
        Supported ports: [ FIBRE ]
        Supported link modes:   1000baseX/Full
                                10000baseCR/Full
                                10000baseSR/Full
                                10000baseLR/Full
                                10000baseER/Full
        Supported pause frame use: Symmetric Receive-only
        Supports auto-negotiation: Yes
        Advertised link modes:  1000baseT/Full
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Speed: 10000Mb/s
        Duplex: Full
        Port: FIBRE
        PHYAD: 0
        Transceiver: external
        Auto-negotiation: off
        Current message level: 0x00000000 (0)
        Link detected: yes
Signed-off-by: Vidya Sagar Ravipati <vidya@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

After resume from hibernate on arm64, any amd-xgbe devices that were
running when we hibernated are reported as down, even when it is not.

Re-plugging the cables does not cause the interface to come back, the
link must be marked as down then up via 'ip set link' using the serial
console.

This happens because the device has been power-cycled and possibly
re-initialised by firmware, whereas the driver's memory structures have
been restored from the hibernate image and the two do not agree.

Schedule a restart of the device after powerup in case the world changed
while we were asleep.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

When TCP operates in lossy environments (between 1 and 10 % packet
losses), many SACK blocks can be exchanged, and I noticed we could
drop them on busy senders, if these SACK blocks have to be queued
into the socket backlog.

While the main cause is the poor performance of RACK/SACK processing,
we can try to avoid these drops of valuable information that can lead to
spurious timeouts and retransmits.

Cause of the drops is the skb->truesize overestimation caused by :

- drivers allocating ~2048 (or more) bytes as a fragment to hold an
  Ethernet frame.

- various pskb_may_pull() calls bringing the headers into skb->head
  might have pulled all the frame content, but skb->truesize could
  not be lowered, as the stack has no idea of each fragment truesize.

The backlog drops are also more visible on bidirectional flows, since
their sk_rmem_alloc can be quite big.

Let's add some room for the backlog, as only the socket owner
can selectively take action to lower memory needs, like collapsing
receive queues or partial ofo pruning.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit b70661c7 ("net: smc91x: use run-time configuration on all ARM
machines") broke some ARM platforms through several mistakes.  Firstly,
the access size must correspond to the following rule:

(a) at least one of 16-bit or 8-bit access size must be supported
(b) 32-bit accesses are optional, and may be enabled in addition to
    the above.

Secondly, it provides no emulation of 16-bit accesses, instead blindly
making 16-bit accesses even when the platform specifies that only 8-bit
is supported.

Reorganise smc91x.h so we can make use of the existing 16-bit access
emulation already provided - if 16-bit accesses are supported, use
16-bit accesses directly, otherwise if 8-bit accesses are supported,
use the provided 16-bit access emulation.  If neither, BUG().  This
exactly reflects the driver behaviour prior to the commit being fixed.

Since the conversion incorrectly cut down the available access sizes on
several platforms, we also need to go through every platform and fix up
the overly-restrictive access size: Arnd assumed that if a platform can
perform 32-bit, 16-bit and 8-bit accesses, then only a 32-bit access
size needed to be specified - not so, all available access sizes must
be specified.

This likely fixes some performance regressions in doing this: if a
platform does not support 8-bit accesses, 8-bit accesses have been
emulated by performing a 16-bit read-modify-write access.

Tested on the Intel Assabet/Neponset platform, which supports only 8-bit
accesses, which was broken by the original commit.

Fixes: b70661c7 ("net: smc91x: use run-time configuration on all ARM machines")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>