This reverts commit e9275f5e. This commit is the
last in the netback grant mapping series, and it tries to do more aggressive
aggreagtion of unmap operations. However practical use showed almost no
positive effect, whilst with certain frontends it causes significant performance
regression.
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Eric W. Biederman says:

====================
Using dev_kfree/consume_skb_any for functions called in multiple contexts

These changes are a result of walking through the network drivers
supporting netpoll and verifying the code paths that netpoll can cause
to be called in hard irq context use an appropriate flavor of
kfree_skb.  Either dev_kfree_skb_any or dev_consume_skb_any.

Since my last pass at this I have become aware of the small differences
between dev_kfree_skb_any and dev_consume_skb_any.
net/core/drop_monitor.c reports the dev_kfree_skb_any as a drop and
while being quite about the second.  With the weird twist that
dev_kfree_skb is unintuitively consume_skb.

As netpoll now calls the napi poll function with budget == 0, pieces of
a drivers the napi poll function that don't run when budget == 0 have
been ignored.

The most interesting change is to the atl1c which tried unsuccesfully to
tell one of it's functions which context it is called in so that it
could call dev_kfree_skb_irq or dev_kfree_skb as appropriate.  I have
just removed the extra parameter and called dev_consume_skb_any.

At 54 separate changes I will post each change as a separate patch (so
they can be reviewed) but for general sanity sake I have gathered them
all into a git branch for easy acces.
====================
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Replace kfree_skb with dev_kfree_skb_any in vlan_insert_tag as
vlan_insert_tag can be called from hard irq context (netpoll)
and from other contexts.

dev_kfree_skb_any is used as vlan_insert_tag only frees the skb if the
skb can not be modified to insert a tag, in which case vlan_insert_tag
drops the skb.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in start_xmit which can
be called in hard irq and other contexts.

start_xmit only frees skbs that it is dropping.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in cvm_oct_xmit_pow which
can be called in hard irq and other contexts, on the code paths that
drop packets.

Replace dev_kfree_skb with dev_consume_skb_any in cvm_oct_xmit_pow which
can be called in hard irq and other contexts, on the code path where
the packet is transmitted successfully.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in wl_send and
wl_send_dma which can be called in hard irq and other contexts,
on the code paths where the skb was transmitted successfully.

Replace dev_kfree_skb with dev_kfree_skb_any in wl_send_dmay which can
be called in hard irq and other contexts, on the code path where a
skb is dropped.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in xennet_start_xmit
which can be called in hard irq and other contexts.  xennet_start_xmit
only fress skbs which it drops.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in vmnet3_tx_xmit which
can be called in hard irq and other contexts.  vmnet3_tx_xmit only
frees skbs that it has dropped.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in xemaclite_send which
can be called in hard irq and other contexts.  xemacelite_send only
frees skbs that it has successfully transmitted.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in velocity_xmit that can
be called in hard irq and other contexts.  Packets are freed and
dropped in velocity_xmit when they are too fragmented and can
not be linearized.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in rhine_start_tx which
can be called in hard irq and other contexts.  Packets are only freed
in rhine_start_tx if they are dropped.

Replace dev_kfree_skb with dev_consume_skb_any in rhine_tx that can be
called in hard irq and other contexts.  rhine_tx handles successfully
transmitted packets.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in
spider_net_release_tx_chain which can be called in hard irq and other
contexts.

dev_consume_skb_any was choosen as it preserves the current
dev_kfree_skb semantics (dev_kfree_skb is consume_skb) and
is because it is correct most of the time as most packets
will have been successfully transmitted not dropeed.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace kfree_skb with dev_consume_skb_any in tile_net_tx and
tile_net_tx_tso which can be called in hard irq and other contexts.

At the point where the skbs are freed a packet has been successfully
transmitted so dev_consume_skb_any is the appropriate variant to use.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in gem_tx which can be
called in hard irq and other contexts.  gem_tx handles successfully
transmitted packets.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in stmmac_tx_clean that can
be called in hard irq and other contexts.  stmmac_tx_clean handles
freeing successfully transmitted packets.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in smsc911x_hard_xmit
which can be called in hard irq and other contexts. smsc911x_hard_xmit
always transmits and consumes the specified skb.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in
smc_hardware_send_pkt that can be called in hard irq and other
contexts, and handles successfully transmitted packets.

Replace dev_kfree_skb with dev_kfree_skb_any in smc_hard_start_xmit which
can be called in hard irq and other contexts, and only frees skbs
when dropping them.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in functions that can
be called in hard irq and other contexts.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in functions that can
be called in hard irq and other contexts.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in sc92031_start_xmit
that can be called in hard irq and other contexts.

Using dev_consume_skb_any preserves the current semantics (as
dev_kfree_skb is just consume_skb) and since packet drops
are rare is usually accurate.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace kfree_skb with dev_kfree_skb_any in functions that can
be called in hard irq and other contexts.

Every location changes is a drop making dev_kfree_skby_any appropriate.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in vxge_xmit that can
be called in hard irq and other contexts.

vxge_xmit only calls dev_kfree_skb_any when errors result in dropping
skbs.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in s2io_xmit that can
be called in hard irq and other contexts.

All instances that are changed are packet drops.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in copy_old_skb that can
be called in hard irq and other contexts.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in sky2_xmit_frame that
can be called in hard irq and other contexts.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any skge_xmit_free that can
be called in hard irq and other contexts, on the path that
handles dropped packets.

Replace dev_kfree_skb with dev_consume_skb_any in skge_tx_done that can
be called in hard irq and other contexts, on the path that handles
successfully transmitted skbs.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in mv643xx_eth_xmit and
txq_submit_skb that can be called in hard irq and other contexts,
on paths where the skbs are dropped.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in jme_expand_header that
can be called in hard irq and other contexts, on the failure
path where the skb is dropped.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in ibmveth_start_xmit
that can be called in hard irq and other contexts.

In this code path the packet can have either been transmitted
or dropped, dev_consume_skb_any was choosen because that preserves
the existing semantics of the code, and a transmitted packet is
more likely.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in functions that can
be called in hard irq and other contexts.

None of the locations was a packet drop so dev_kfree_skb_any is
inappropriate.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in i596_start_xmit that
can be called in hard irq and other contexts, when the skb is dropped.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in ucc_geth_tx that can
be called in hard irq and other contexts, when processing the
tx completion event.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace kfree_skb with dev_kfree_skb_any in fec_enet_start_xmit that
can be called in hard irq and other contexts, when the packet is
dropped.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in start_tx that can
be called in hard irq and other contexts, when the skb is dropped.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in uli562x_start_xmit
that can be called in hard irq and other contexts, when the packet is
dropped.

Replace dev_kfree_skb with dev_consume_skb_any in uli562x_start_xmit
that can be called in hard irq and other contexts, when the packet is
transmitted.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in dmfe_start_xmit that
can be called in hard irq and other contexts, when the packet is
dropped.

Replace dev_kfree_skb with dev_consume_skb_any in dmfe_start_xmit that
can be called in hard irq and other contexts, when the packet is
transmitted.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in dm9000_start_xmit
that can be called in hard irq and other contexts, on the path
that successfully transmits the packet.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_kfree_skb_any in enic_hard_start_xmit
that can be called in hard irq and other contexts.

enic_hard_start_xmit only frees the skb when dropping it.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace dev_kfree_skb with dev_consume_skb_any in net_send_packet that
can be called in hard irq and other contexts.

net_send_packet consumes (not drops) the skb of interest.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Replace kfree_skb with dev_consume_skb_any in free_tx_desc that can be
called in hard irq and other contexts. dev_consume_skb_any is used
as this function consumes successfully transmitted skbs.

Replace dev_kfree_skb with dev_kfree_skb_any in t4vf_eth_xmit that can
be called in hard irq and other contexts, on paths that drop the skb.

Replace dev_kfree_skb with dev_consume_skb_any in t4vf_eth_xmit that can
be called in hard irq and other contexts, on paths that successfully
transmit the skb.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>