tcp_splice_read() doesnt take into account socket's O_NONBLOCK flag
Before this patch :
splice(socket,0,pipe,0,128*1024,SPLICE_F_MOVE);
causes a random endless block (if pipe is full) and
splice(socket,0,pipe,0,128*1024,SPLICE_F_MOVE | SPLICE_F_NONBLOCK);
will return 0 immediately if the TCP buffer is empty.
User application has no way to instruct splice() that socket should be in blocking mode
but pipe in nonblock more.
Many projects cannot use splice(tcp -> pipe) because of this flaw.
http://git.samba.org/?p=samba.git;a=history;f=source3/lib/recvfile.c;h=ea0159642137390a0f7e57a123684e6e63e47581;hb=HEADhttp://lkml.indiana.edu/hypermail/linux/kernel/0807.2/0687.html
Linus introduced SPLICE_F_NONBLOCK in commit 29e350944f
(splice: add SPLICE_F_NONBLOCK flag )
It doesn't make the splice itself necessarily nonblocking (because the
actual file descriptors that are spliced from/to may block unless they
have the O_NONBLOCK flag set), but it makes the splice pipe operations
nonblocking.
Linus intention was clear : let SPLICE_F_NONBLOCK control the splice pipe mode only
This patch instruct tcp_splice_read() to use the underlying file O_NONBLOCK
flag, as other socket operations do.
Users will then call :
splice(socket,0,pipe,0,128*1024,SPLICE_F_MOVE | SPLICE_F_NONBLOCK );
to block on data coming from socket (if file is in blocking mode),
and not block on pipe output (to avoid deadlock)
First version of this patch was submitted by Octavian Purdila
Reported-by: Volker Lendecke <vl@samba.org>
Reported-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch against v2.6.31 adds support for route lookup using sk_mark in some
more places. The benefits from this patch are the following.
First, SO_MARK option now has effect on UDP sockets too.
Second, ip_queue_xmit() and inet_sk_rebuild_header() could fail to do routing
lookup correctly if TCP sockets with SO_MARK were used.
Signed-off-by: Atis Elsts <atis@mikrotik.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
This is based on Michal Schmidt fix for skge.
Most network drivers request their IRQ when the interface is activated.
sky2 does it in ->probe() instead, because it can work with two-port
cards where the two net_devices use the same IRQ. This works fine most
of the time, except in some situations when the interface gets renamed.
Consider this example:
1. modprobe sky2
The card is detected as eth0 and requests IRQ 17. Directory
/proc/irq/17/eth0 is created.
2. There is an udev rule which says this interface should be called
eth1, so udev renames eth0 -> eth1.
3. modprobe 8139too
The Realtek card is detected as eth0. It will be using IRQ 17 too.
4. ip link set eth0 up
Now 8139too requests IRQ 17.
The result is:
WARNING: at fs/proc/generic.c:590 proc_register ...
proc_dir_entry '17/eth0' already registered
The fix is for sky2 to name the irq based on the pci device, as is done
by some other devices DRM, infiniband, ... ie. sky2@pci:0000:00:00
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Reviewed-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Most network drivers request their IRQ when the interface is activated.
skge does it in ->probe() instead, because it can work with two-port
cards where the two net_devices use the same IRQ. This works fine most
of the time, except in some situations when the interface gets renamed.
Consider this example:
1. modprobe skge
The card is detected as eth0 and requests IRQ 17. Directory
/proc/irq/17/eth0 is created.
2. There is an udev rule which says this interface should be called
eth1, so udev renames eth0 -> eth1.
3. modprobe 8139too
The Realtek card is detected as eth0. It will be using IRQ 17 too.
4. ip link set eth0 up
Now 8139too requests IRQ 17.
The result is:
WARNING: at fs/proc/generic.c:590 proc_register ...
proc_dir_entry '17/eth0' already registered
...
And "ls /proc/irq/17" shows two subdirectories, both called eth0.
Fix it by using a unique name for skge's IRQ, based on the PCI address.
The naming from the example then looks like this:
$ grep skge /proc/interrupts
17: 169 IO-APIC-fasteoi skge@pci:0000:00:0a.0, eth0
irqbalance daemon will have to be taught to recognize "skge@" as an
Ethernet interrupt. This will be a one-liner addition in classify.c. I
will send a patch to irqbalance if this change is accepted.
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acknowledge TCP window scale support by inserting the proper option in SYN/ACK
and SYN headers even if our window scale is zero.
This fixes the following observed behavior:
1. Client sends a SYN with TCP window scaling option and non zero window scale
value to a Linux box.
2. Linux box notes large receive window from client.
3. Linux decides on a zero value of window scale for its part.
4. Due to compare against requested window scale size option, Linux does not to
send windows scale TCP option header on SYN/ACK at all.
With the following result:
Client box thinks TCP window scaling is not supported, since SYN/ACK had no
TCP window scale option, while Linux thinks that TCP window scaling is
supported (and scale might be non zero), since SYN had TCP window scale
option and we have a mismatched idea between the client and server
regarding window sizes.
Probably it also fixes up the following bug (not observed in practice):
1. Linux box opens TCP connection to some server.
2. Linux decides on zero value of window scale.
3. Due to compare against computed window scale size option, Linux does
not to set windows scale TCP option header on SYN.
With the expected result that the server OS does not use window scale option
due to not receiving such an option in the SYN headers, leading to suboptimal
performance.
Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com>
Signed-off-by: Ori Finkelman <ori@comsleep.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/tcp.c: In function 'do_tcp_setsockopt':
net/ipv4/tcp.c:2050: warning: comparison of distinct pointer types lacks a cast
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove references to dead web site mosquitonet.Stanford.EDU.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This typo was introduced by 5793f4be23 on
October 14, 2005 ...
Reported-by: Matti Aarnio <matti.aarnio@zmailer.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
prev_vlan_tag field is not used.
Patch saves 512*8 bytes per tx queue ring on 64bit arches.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Matthew Carlson <mcarlson@broadcom.com>
The function virtnet_remove is used only wrapped by __devexit_p so define
it using __devexit.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Alex Williamson <alex.williamson@hp.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
The function sgiseeq_remove is defined using __exit, so don't use
__devexit_p but __exit_p to wrap it.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Wang Chen <wangchen@cn.fujitsu.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
The function meth_remove is defined using __exit, so don't use __devexit_p
but __exit_p to wrap it.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
Primary module parameter passed to bonding is pernament. That means if you
release the primary slave and enslave it again, it becomes the primary slave
again. But if you set primary slave via sysfs, the primary slave is only set
once and it's not remembered in bond->params structure. Therefore the setting is
lost after releasing the primary slave. This simple one-liner fixes this.
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
After last pktgen changes, delay handling is wrong.
pktgen actually sends packets at full line speed.
Fix is to update pkt_dev->next_tx even if spin() returns early,
so that next spin() calls have a chance to see a positive delay.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ccffad25b5 changed parameters for function
ixgbe_update_uc_addr_list_generic but parameter description was not updated.
This patch corrects it.
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
vtp bit in RX completion descriptor could be wrongly set in
some skews of BladEngine. Ignore this bit if vtm is not set.
Resending because the previous patch was against net-next tree.
This patch is against the net-2.6 tree.
Signed-off-by: Ajit Khaparde <ajitk@serverengines.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As noticed by Alan Stern, there is still one issue with the driver:
we disable PCI IRQ on suspend, but other devices on the same IRQ
line might still need the IRQ enabled to suspend properly.
Nowadays, PCI core handles all power management work by itself, with
one condition though: if we use dev_pm_ops. So, rework the driver to
only quiesce 3c59x internal logic on suspend, while PCI core will
manage PCI device power state with IRQs disabled.
Suggested-by: Rafael J. Wysocki <rjw@sisk.pl>
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is the first registration of ks8851 network driver with
MLL(address/data multiplexed) interface.
Signed-off-by : David J. Choi <david.choi@micrel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If allocation of the second ports fails, make sure that hw->ports
is not 2 otherwise we'll crash trying to access the second port.
This fix is copied from a similar fix in the sky2 driver (ca519274...),
but is untested, as I don't have a skge card.
Signed-off-by: Mike McCormack <mikem@ring3k.org>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
`while (limit-- >= 0)' reaches -2 after the loop upon timeout.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Move the call to rtnl_lock() to before the internal call to
ql_adapter_down()/ql_adapter_up(). This prevents collisions that can
happen when recovering from an asic error.
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ql_clear_routing_entries() takes/gives it's own hardware semaphore since
it is called from more than one place. ql_route_initialize() should
make this call and THEN take it's own semaphore before doing it's work.
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ATR support for UDP on 82599 needs to be redesigned, since the
current model doesn't make much sense. The fallout from having
it in though is it causes all UDP traffic to still compute the
ATR hashes on transmit, which are useless. This removal will
return upwards of 10% of relative computational overhead in
forwarding tests.
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When LRO is enabled, the received packet and byte counters represent the
LRO'd packets, not the packets/bytes on the wire. The Intel 82599 NIC has
registers that keep count of the physical packets. Add these counters to
the ethtool stats. The byte counters are 36-bit, but the high 4 bits were
being ignored in the 2.6.31 ixgbe driver: Read those as well to allow
longer time between polling the stats to detect wraps.
Signed-off-by: Ben Greear <greearb@candelatech.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
A number of changes have gone in since the last version bump. Bump
it to reflect the changes.
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Backplane flow control autonegotiation is currently broken for
ixgbe devices. This patch fixes the flow control issues
with clause 37 autoneg.
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
82599 has a different register offset for the Tx DCA control registers.
We disable relaxed ordering of the descriptor writebacks for Tx head
writeback, but didn't disable it properly for 82599. However, this
shouldn't be a visible issue, since ixgbe doesn't use Tx head writeback.
This patch just makes sure we're not doing blind writes to offsets we
don't expect.
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In ax25_make_new, if kmemdup of digipeat returns an error, there would
be an oops in sk_free while calling sk_destruct, because sk_protinfo
is NULL at the moment; move sk->sk_destruct initialization after this.
BTW of reported-by: Bernard Pidoux F6BVP <f6bvp@free.fr>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since commit 9b22ea5609
( net: fix packet socket delivery in rx irq handler )
We lost rx timestamping of packets received on accelerated vlans.
Effect is that tcpdump on real dev can show strange timings, since it gets rx timestamps
too late (ie at skb dequeueing time, not at skb queueing time)
14:47:26.986871 IP 192.168.20.110 > 192.168.20.141: icmp 64: echo request seq 1
14:47:26.986786 IP 192.168.20.141 > 192.168.20.110: icmp 64: echo reply seq 1
14:47:27.986888 IP 192.168.20.110 > 192.168.20.141: icmp 64: echo request seq 2
14:47:27.986781 IP 192.168.20.141 > 192.168.20.110: icmp 64: echo reply seq 2
14:47:28.986896 IP 192.168.20.110 > 192.168.20.141: icmp 64: echo request seq 3
14:47:28.986780 IP 192.168.20.141 > 192.168.20.110: icmp 64: echo reply seq 3
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
From: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
port_mutex was unlocked twice.
Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When requesting all prl entries (kprl.addr == INADDR_ANY) and there are
more prl entries than there is space passed from userspace, the existing
code would always copy cmax+1 entries, which is more than can be handled.
This patch makes the kernel copy only exactly cmax entries.
Signed-off-by: Sascha Hlusiak <contact@saschahlusiak.de>
Acked-By: Fred L. Templin <Fred.L.Templin@boeing.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 2b85a34e91
(net: No more expensive sock_hold()/sock_put() on each tx)
opens a window in sock_wfree() where another cpu
might free the socket we are working on.
A fix is to call sk->sk_write_space(sk) while still
holding a reference on sk.
Reported-by: Jike Song <albcamus@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This provides safety against negative optlen at the type
level instead of depending upon (sometimes non-trivial)
checks against this sprinkled all over the the place, in
each and every implementation.
Based upon work done by Arjan van de Ven and feedback
from Linus Torvalds.
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch fixes a embarrassing bug which was introduced by:
"[PATCH] ar9170: implement frequency calibration for one-stage/openfw"
The phy_data variable initialization has to done outside the for-loop
scope. This is because the for-loop uses u32 phy_data variable more
like a 4-byte field. But in each run only a single byte is calculated.
Therefore phy_data content needs to stay the same for at least 3 more
iterations, before the complete set can be uploaded.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Thrustmaster FunAccess WIFI USB works with rt73usb with little
modification of rt73usb.c.
Tested with version 2.3.0 of driver.
Signed-off-by: Michal Szalata <szalat@gmail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
mac80211_hwsim does not start transmitting Beacon frames when hostapd
is started for the first time and restarting hostapd fixes this. The
issue is caused by the config() handler not being able to start
beacon_timer when beacon interval is not yet known and
bss_info_changed() handler not starting the timer. This can be fixed by
making the bss_info_changed() update the timer.
Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
On SDIO the PIO data register seems to be hardwired to LE. So
the MACCTL bit has no effect on the endianness.
So also use block-I/O for the last word of the packet. block-I/O is always LE.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Tested-by: Albert Herranz <albert_herranz@yahoo.es>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Consider the following step-by step:
1. A STA authenticates and associates with the AP and exchanges
traffic.
2. The STA reports to the AP that it is going to PS state.
3. Some time later the STA device goes to the stand-by mode (not only
its wi-fi card, but the device itself) and drops the association state
without sending a disassociation frame.
4. The STA device wakes up and begins authentication with an
Auth frame as it hasn't been authenticated/associated previously.
At the step 4 the AP "remembers" the STA and considers it is still in
the PS state, so the AP buffers frames, which it has to send to the STA.
But the STA isn't actually in the PS state and so it neither checks
TIM bits nor reports to the AP that it isn't power saving.
Because of that authentication/[re]association fails.
To fix authentication/[re]association stage of this issue, Auth, Assoc
Resp and Reassoc Resp frames are transmitted disregarding of STA's power
saving state.
N.B. This patch doesn't fix further data frame exchange after
authentication/[re]association. A patch in hostapd is required to fix
that.
Signed-off-by: Igor Perminov <igor.perminov@inbox.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Without this, the hard-blocked state will be reported incorrectly if
the hardware switch is changed while the laptop is suspended.
Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Tested-by: Norbert Preining <preining@logic.at>
Acked-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
"I recently (on a flight) I found out that when I boot with the hard-switch
activated, so turning off all wireless activity on my laptop, the state
is not correctly announced in /dev/rfkill (reading it with rfkill command,
or my own gnome applet)...
After turning off and on again the hard-switch the events were right."
We can fix this by querying the firmware at load time and calling
rfkill_set_hw_state().
Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Tested-by: Norbert Preining <preining@logic.at>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Mattia Dongili <malattia@linux.it>
CC: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>
The move away from having drivers assign wireless handlers,
in favour of making cfg80211 assign them, broke the sysfs
registration (the wireless/ dir went missing) because the
handlers are now assigned only after registration, which is
too late.
Fix this by special-casing cfg80211-based devices, all
of which are required to have an ieee80211_ptr, in the
sysfs code, and also using get_wireless_stats() to have
the same values reported as in procfs.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Reported-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Tested-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
The wireless extensions have a copy_from_user to a local stack
array "essid", but both me and gcc have failed to find where
the bounds for this copy are located in the code.
This patch adds some basic sanity checks for the copy length
to make sure that we don't overflow the stack buffer.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>
It's useful to know the MAC address when being
disassociated; fix a typo (missing colon) and
move some messages so we get them only when they
are actually taking effect.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Multiple problems were reported due to interaction
between wpa_supplicant and the wext compat code in
cfg80211, which appear to be due to it not getting
any bss pointer here when wpa_supplicant sets all
parameters -- do that now. We should still get the
bss after doing an extra scan, but that appears to
increase the time we need for connecting enough to
sometimes cause timeouts.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Tested-by: Hin-Tak Leung <hintak.leung@gmail.com>,
Signed-off-by: John W. Linville <linville@tuxdriver.com>
When hardware or uCode problem occurs driver captures significant
information from device to enable debugging. The format of this information
is different between 3945 and 4965 and later devices, yet currently the
3945 uses the 4965 and later format. Fix this by adding a new library call
that is initialized to the correct formatting routine based on device.
This moves the iwlagn event and error log handling back to iwl-agn.c to
make it part of iwlagn module.
Also remove the 3945 sysfs file that triggers dump of event log - there is
already a debugfs file that can do it for all drivers.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>