Supply dm_add_exception as a callback to the read_metadata function.
Add a status function ready for a later patch and name the functions
consistently.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Move the existing snapshot exception store implementations out into
separate files. Later patches will place these behind a new
interface in preparation for alternative implementations.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Rename struct exception_store to dm_exception_store.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Pull structures that bridge the gap between snapshot and
exception store out of dm-snap.h and put them in a new
.h file - dm-exception-store.h. This file will define the
API for new exception stores.
Ultimately, dm-snap.h is unnecessary, since only dm-snap.c
should be using it.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
The same workqueue is used both for sending uevents and processing queued I/O.
Deadlock has been reported in RHEL5 when sending a uevent was blocked waiting
for the queued I/O to be processed. Use scheduled_work() for the asynchronous
uevents instead.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Implement simple read-only sysfs entry for device-mapper block device.
This patch adds a simple sysfs directory named "dm" under block device
properties and implements
- name attribute (string containing mapped device name)
- uuid attribute (string containing UUID, or empty string if not set)
The kobject is embedded in mapped_device struct, so no additional
memory allocation is needed for initializing sysfs entry.
During the processing of sysfs attribute we need to lock mapped device
which is done by a new function dm_get_from_kobj, which returns the md
associated with kobject and increases the usage count.
Each 'show attribute' function is responsible for its own locking.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Rework table reference counting.
The existing code uses a reference counter. When the last reference is
dropped and the counter reaches zero, the table destructor is called.
Table reference counters are acquired/released from upcalls from other
kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
If the reference counter reaches zero in one of the upcalls, the table
destructor is called from almost random kernel code.
This leads to various problems:
* dm_any_congested being called under a spinlock, which calls the
destructor, which calls some sleeping function.
* the destructor attempting to take a lock that is already taken by the
same process.
* stale reference from some other kernel code keeps the table
constructed, which keeps some devices open, even after successful
return from "dmsetup remove". This can confuse lvm and prevent closing
of underlying devices or reusing device minor numbers.
The patch changes reference counting so that the table destructor can be
called only at predetermined places.
The table has always exactly one reference from either mapped_device->map
or hash_cell->new_map. After this patch, this reference is not counted
in table->holders. A pair of dm_create_table/dm_destroy_table functions
is used for table creation/destruction.
Temporary references from the other code increase table->holders. A pair
of dm_table_get/dm_table_put functions is used to manipulate it.
When the table is about to be destroyed, we wait for table->holders to
reach 0. Then, we call the table destructor. We use active waiting with
msleep(1), because the situation happens rarely (to one user in 5 years)
and removing the device isn't performance-critical task: the user doesn't
care if it takes one tick more or not.
This way, the destructor is called only at specific points
(dm_table_destroy function) and the above problems associated with lazy
destruction can't happen.
Finally remove the temporary protection added to dm_any_congested().
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Implement barrier support for single device DM devices
This patch implements barrier support in DM for the common case of dm linear
just remapping a single underlying device. In this case we can safely
pass the barrier through because there can be no reordering between
devices.
NB. Any DM device might cease to support barriers if it gets
reconfigured so code must continue to allow for a possible
-EOPNOTSUPP on every barrier bio submitted. - agk
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Allow NULL buffer in dm_copy_name_and_uuid if you only want to return one of
the fields.
(Required by a following patch that adds these fields to sysfs.)
Signed-off-by: Milan Broz <mbroz@redhat.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Check that the log bitmap will fit within the log device.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Move log size validation from mirror target to log constructor.
Removed PAGE_SIZE restriction we no longer think necessary.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
rw_header function updates three members of io_req data every time
when I/O is processed. bi_rw and notify.fn are never modified once
they get initialized, and so they can be set in advance.
header_to_disk() can also be pulled out of write_header() since only one
caller needs it and write_header() can be replaced by rw_header()
directly.
Signed-off-by: Takahiro Yasui <tyasui@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Change dm_unregister_target to return void and use BUG() for error
reporting.
dm_unregister_target can only fail because of programming bug in the
target driver. It can't fail because of user's behavior or disk errors.
This patch changes unregister_target to return void and use BUG if
someone tries to unregister non-registered target or unregister target
that is in use.
This patch removes code duplication (testing of error codes in all dm
targets) and reports bugs in just one place, in dm_unregister_target. In
some target drivers, these return codes were ignored, which could lead
to a situation where bugs could be missed.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Always increase the error count when I/O on a leg of a mirror fails.
The error count is used to decide whether to select an alternative
mirror leg. If the target doesn't use the "handle_errors" feature, the
error count is not updated and the bio can get requeued forever by the
read callback.
Fix it by increasing error_count before the handle_errors feature
checking.
Cc: stable@kernel.org
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
In create_log_context function, dm_io_client_destroy function needs
to be called, when memory allocation of disk_header, sync_bits and
recovering_bits failed, but dm_io_client_destroy is not called.
Cc: stable@kernel.org
Signed-off-by: Takahiro Yasui <tyasui@redhat.com>
Acked-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Change yield() to msleep(1). If the thread had realtime priority,
yield() doesn't really yield, so the yielding process would loop
indefinitely and cause machine lockup.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Move one dm_table_put() so that the last reference in the thread
gets dropped in __unbind().
This is required for a following patch,
dm-table-rework-reference-counting.patch, which will change the logic in
such a way that table destructor is called only at specific points in
the code.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* 'i2c-next' of git://aeryn.fluff.org.uk/bjdooks/linux:
i2c-omap: fix type of irq handler function
i2c-s3c2410: Change IRQ to be plain integer.
i2c-s3c2410: Allow more than one i2c-s3c2410 adapter
i2c-s3c2410: Remove default platform data.
i2c-s3c2410: Use platform data for gpio configuration
i2c-s3c2410: Fixup style problems from checkpatch.pl
i2c-omap: Enable I2C wakeups for 34xx
i2c-omap: reprogram OCP_SYSCONFIG register after reset
i2c-omap: convert 'rev1' flag to generic 'rev' u8
i2c-omap: fix I2C timeouts due to recursive omap_i2c_{un,}idle()
i2c-omap: Clean-up i2c-omap
i2c-omap: Don't compile in OMAP15xx I2C ISR for non-OMAP15xx builds
i2c-omap: Mark init-only functions as __init
i2c-omap: Add support for omap34xx
i2c-omap: FIFO handling support and broken hw workaround for i2c-omap
i2c-omap: Add high-speed support to omap-i2c
i2c-omap: Close suspected race between omap_i2c_idle() and omap_i2c_isr()
i2c-omap: Do not use interruptible wait call in omap_i2c_xfer_msg
Fix up apparently-trivial conflict in drivers/i2c/busses/i2c-s3c2410.c
When using "min()", the types of both sides should match. With the cpu
mask changes, the type of num_online_cpus() will now depend on config
options. Use "min_t()" with an explicit type instead.
And make the rx/tx case look the same too, just for sanity.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (44 commits)
qlge: Fix sparse warnings for tx ring indexes.
qlge: Fix sparse warning regarding rx buffer queues.
qlge: Fix sparse endian warning in ql_hw_csum_setup().
qlge: Fix sparse endian warning for inbound packet control block flags.
qlge: Fix sparse warnings for byte swapping in qlge_ethool.c
myri10ge: print MAC and serial number on probe failure
pkt_sched: cls_u32: Fix locking in u32_change()
iucv: fix cpu hotplug
af_iucv: Free iucv path/socket in path_pending callback
af_iucv: avoid left over IUCV connections from failing connects
af_iucv: New error return codes for connect()
net/ehea: bitops work on unsigned longs
Revert "net: Fix for initial link state in 2.6.28"
tcp: Kill extraneous SPLICE_F_NONBLOCK checks.
tcp: don't mask EOF and socket errors on nonblocking splice receive
dccp: Integrate the TFRC library with DCCP
dccp: Clean up ccid.c after integration of CCID plugins
dccp: Lockless integration of CCID congestion-control plugins
qeth: get rid of extra argument after printk to dev_* conversion
qeth: No large send using EDDP for HiperSockets.
...
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
[CPUFREQ] Fix on resume, now preserves user policy min/max.
[CPUFREQ] Add Celeron Core support to p4-clockmod.
[CPUFREQ] add to speedstep-lib additional fsb values for core processors
[CPUFREQ] Disable sysfs ui for p4-clockmod.
[CPUFREQ] p4-clockmod: reduce noise
[CPUFREQ] clean up speedstep-centrino and reduce cpumask_t usage
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
inotify: fix type errors in interfaces
fix breakage in reiserfs_new_inode()
fix the treatment of jfs special inodes
vfs: remove duplicate code in get_fs_type()
add a vfs_fsync helper
sys_execve and sys_uselib do not call into fsnotify
zero i_uid/i_gid on inode allocation
inode->i_op is never NULL
ntfs: don't NULL i_op
isofs check for NULL ->i_op in root directory is dead code
affs: do not zero ->i_op
kill suid bit only for regular files
vfs: lseek(fd, 0, SEEK_CUR) race condition
Warnings:
drivers/net/qlge/qlge_main.c:1474:34: warning: restricted degrades to integer
drivers/net/qlge/qlge_main.c:1475:36: warning: restricted degrades to integer
drivers/net/qlge/qlge_main.c:1592:51: warning: restricted degrades to integer
drivers/net/qlge/qlge_main.c:1941:20: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:1941:20: expected restricted unsigned int [usertype] tid
drivers/net/qlge/qlge_main.c:1941:20: got int [signed] index
drivers/net/qlge/qlge_main.c:1945:24: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:1945:24: expected restricted unsigned int [usertype] txq_idx
drivers/net/qlge/qlge_main.c:1945:24: got unsigned int [unsigned] [usertype] tx_ring_idx
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Warnings:
drivers/net/qlge/qlge_main.c:909:17: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:909:17: expected unsigned int [unsigned] [usertype] addr_lo
drivers/net/qlge/qlge_main.c:909:17: got restricted unsigned int [usertype] <noident>
drivers/net/qlge/qlge_main.c:911:17: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:911:17: expected unsigned int [unsigned] [usertype] addr_hi
drivers/net/qlge/qlge_main.c:911:17: got restricted unsigned int [usertype] <noident>
drivers/net/qlge/qlge_main.c:974:17: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:974:17: expected unsigned int [unsigned] [usertype] addr_lo
drivers/net/qlge/qlge_main.c:974:17: got restricted unsigned int [usertype] <noident>
drivers/net/qlge/qlge_main.c:975:17: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:975:17: expected unsigned int [unsigned] [usertype] addr_hi
drivers/net/qlge/qlge_main.c:975:17: got restricted unsigned int [usertype] <noident>
drivers/net/qlge/qlge_main.c:2132:16: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:2132:16: expected unsigned int [unsigned] [usertype] addr_lo
drivers/net/qlge/qlge_main.c:2132:16: got restricted unsigned int [usertype] <noident>
drivers/net/qlge/qlge_main.c:2133:16: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:2133:16: expected unsigned int [unsigned] [usertype] addr_hi
drivers/net/qlge/qlge_main.c:2133:16: got restricted unsigned int [usertype] <noident>
drivers/net/qlge/qlge_main.c:2212:15: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:2212:15: expected unsigned int [unsigned] [usertype] addr_lo
drivers/net/qlge/qlge_main.c:2212:15: got restricted unsigned int [usertype] <noident>
drivers/net/qlge/qlge_main.c:2214:15: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:2214:15: expected unsigned int [unsigned] [usertype] addr_hi
drivers/net/qlge/qlge_main.c:2214:15: got restricted unsigned int [usertype] <noident>
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changed u16 to __sum16 usage.
Warnings:
drivers/net/qlge/qlge_main.c:1897:9: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:1897:9: expected unsigned short [usertype] *check
drivers/net/qlge/qlge_main.c:1897:9: got restricted unsigned short *<noident>
drivers/net/qlge/qlge_main.c:1903:9: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:1903:9: expected unsigned short [usertype] *check
drivers/net/qlge/qlge_main.c:1903:9: got restricted unsigned short *<noident>
drivers/net/qlge/qlge_main.c:1909:9: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_main.c:1909:9: expected unsigned short [unsigned] [short] [usertype] <noident>
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changed flags element from __le32 to 3 reserved bytes and one byte of
flags. Changed flags bit definitions to reflect byte width instead of
__le32 width.
Warnings:
drivers/net/qlge/qlge_main.c:1206:16: warning: restricted degrades to integer
drivers/net/qlge/qlge_main.c:1207:16: warning: restricted degrades to integer
drivers/net/qlge/qlge_main.c:1233:17: warning: restricted degrades to integer
drivers/net/qlge/qlge_main.c:1276:17: warning: restricted degrades to integer
drivers/net/qlge/qlge_main.c:1349:19: warning: restricted degrades to integer
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/qlge/qlge_ethtool.c:59:23: warning: cast to restricted type
drivers/net/qlge/qlge_ethtool.c:59:21: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_ethtool.c:59:21: expected restricted unsigned short [usertype] irq_delay
drivers/net/qlge/qlge_ethtool.c:59:21: got unsigned short [unsigned] [usertype] <noident>
drivers/net/qlge/qlge_ethtool.c:61:8: warning: cast to restricted type
drivers/net/qlge/qlge_ethtool.c:60:21: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_ethtool.c:60:21: expected restricted unsigned short [usertype] pkt_delay
drivers/net/qlge/qlge_ethtool.c:60:21: got unsigned short [unsigned] [usertype] <noident>
drivers/net/qlge/qlge_ethtool.c:82:23: warning: cast to restricted type
drivers/net/qlge/qlge_ethtool.c:82:21: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_ethtool.c:82:21: expected restricted unsigned short [usertype] irq_delay
drivers/net/qlge/qlge_ethtool.c:82:21: got unsigned short [unsigned] [usertype] <noident>
drivers/net/qlge/qlge_ethtool.c:84:8: warning: cast to restricted type
drivers/net/qlge/qlge_ethtool.c:83:21: warning: incorrect type in assignment (different base types)
drivers/net/qlge/qlge_ethtool.c:83:21: expected restricted unsigned short [usertype] pkt_delay
drivers/net/qlge/qlge_ethtool.c:83:21: got unsigned short [unsigned] [usertype] <noident>
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
To help board identification and diagnosis, print the MAC
and serial number on probe failure if they are available.
Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The flags field of struct ehea_port is only used with test_bit(),
clear_bit() and set_bit() and these interfaces only work on
"unsigned long"s, so change the field to be an "unsigned long". Also,
this field only has two bits defined for it (0 and 1) so will still be
fine if someone builds this driver for a 32 bit arch (at least as far as
this flags field is concerned).
Also note that ehea_driver_flags is only used in ehca_main.c, so make it
static in there.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fsync currently has a fdatawrite/fdatawait pair around the method call,
and a mutex_lock/unlock of the inode mutex. All callers of fsync have
to duplicate this, but we have a few and most of them don't quite get
it right. This patch adds a new vfs_fsync that takes care of this.
It's a little more complicated as usual as ->fsync might get a NULL file
pointer and just a dentry from nfsd, but otherwise gets afile and we
want to take the mapping and file operations from it when it is there.
Notes on the fsync callers:
- ecryptfs wasn't calling filemap_fdatawrite / filemap_fdatawait on the
lower file
- coda wasn't calling filemap_fdatawrite / filemap_fdatawait on the host
file, and returning 0 when ->fsync was missing
- shm wasn't calling either filemap_fdatawrite / filemap_fdatawait nor
taking i_mutex. Now given that shared memory doesn't have disk
backing not doing anything in fsync seems fine and I left it out of
the vfs_fsync conversion for now, but in that case we might just
not pass it through to the lower file at all but just call the no-op
simple_sync_file directly.
[and now actually export vfs_fsync]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and don't bother in callers. Don't bother with zeroing i_blocks,
while we are at it - it's already been zeroed.
i_mode is not worth the effort; it has no common default value.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
drivers/s390/net/qeth_l3_main.c: In function 'qeth_l3_setadapter_parms':
drivers/s390/net/qeth_l3_main.c:1049: warning: too many arguments for format
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
From: Klaus-Dieter Wacker <kdwacker@de.ibm.com>
The device driver qeth dos not support large send using EDDP for
HiperSockets.
Signed-off-by: Klaus-Dieter Wacker <kdwacker@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The ip assist hw command for setting an IP address last unacceptable
long so we can not spin while we waiting for the irq. Since we can
ensure process context for all occurrences of this command we can use
wait.
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
For z/VM GuestLAN or VSWITCH devices the transport layer is
configured in z/VM. The layer2 attribute of a participating Linux
device has to match the z/VM definition. In case of a mismatch
Linux currently crashes in qeth recovery due to a reference to the
not yet existing net_device.
Solution: add a check for existence of net_device and add a message
pointing to the mismatch of layer definitions in Linux and z/VM.
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
OSA-devices operating in layer3 mode offer adding of the source MAC
address to the QDIO header of inbound packets. The qeth driver can
exploit this functionality to replace FAKELL-entries in the ethernet
header of received packets.
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The pre z9 machines provide an mcl string in EBCDIC format,
z9 or later provide string in ASCII format.
Signed-off-by: Klaus-Dieter Wacker <kdwacker@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
register_pernet_gen_device() expects 'int*', found via sparse.
CHECK drivers/net/tun.c
drivers/net/tun.c:1245:36: warning: incorrect type in argument 1 (different signedness)
drivers/net/tun.c:1245:36: expected int *id
drivers/net/tun.c:1245:36: got unsigned int static [toplevel] *<noident>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add missing space after if, switch, for and while keywords.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some indexed registers do not have error bits. In these cases a
value of zero should be used for error checking.
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The length field for these rings is 16-bits. If the length is
the max supported 65536 then the setting should be zero.
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Shadow registers are consistent memory locations to which the chip
echos ring indexes in little endian format. These values need to
be endian swapped before referencing.
Note:
The register pointer declaration uses the volatile modifier which
causes warnings in checkpatch.
Per Documentation/volatile-considered-harmful.txt:
- Pointers to data structures in coherent memory which might be modified
by I/O devices can, sometimes, legitimately be volatile. A ring buffer
used by a network adapter, where that adapter changes pointers to
indicate which descriptors have been processed, is an example of this
type of situation.
Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
