Lengths and types of breakpoints are encoded in a half byte
into CPU registers. However when we extract these values
and store them, we add a high half byte part to them: 0x40 to the
length and 0x80 to the type.
When that gets reloaded to the CPU registers, the high part
is masked.
While making the instruction breakpoints available for perf,
I zapped that high part on instruction breakpoint encoding
and that broke the arch -> generic translation used by ptrace
instruction breakpoints. Writing dr7 to set an inst breakpoint
was then failing.
There is no apparent reason for these high parts so we could get
rid of them altogether. That's an invasive change though so let's
do that later and for now fix the problem by restoring that inst
breakpoint high part encoding in this sole patch.
Reported-by: Kelvie Wong <kelvie@ieee.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
The cap_snap creation/queueing relies on both the current i_head_snapc
_and_ the i_snap_realm pointers being correct, so that the new cap_snap
can properly reference the old context and the new i_head_snapc can be
updated to reference the new snaprealm's context. To fix this, we:
- move inodes completely to the new (split) realm so that i_snap_realm
is correct, and
- generate the new snapc's _before_ queueing the cap_snaps in
ceph_update_snap_trace().
Signed-off-by: Sage Weil <sage@newdream.net>
drivers/firewire/nosy* is a stand-alone driver that does not depend on
CONFIG_FIREWIRE. Hence let make descend into drivers/firewire/ also
if that option is off.
The stand-alone driver drivers/ieee1394/init_ohci1394_dma* will soon be
moved into drivers/firewire/ too and will require the same makefile fix.
Side effect:
As mentioned in https://bugzilla.novell.com/show_bug.cgi?id=586172#c24
this influences the order in which either firewire-ohci or ohci1394 is
going to be bound to an OHCI-1394 controller in case of a modular build
of both drivers if no modprobe blacklist entries are configured.
However, a user of such a setup cannot expect deterministic behavior
anyway. The Kconfig help and the migration guide at
ieee1394.wiki.kernel.org recommend blacklist entries when a dual
IEEE 1394 stack build is being used. (The coexistence period of the two
stacks is planned to end soon.)
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The PCM proc files may open a race against substream close, which can
end up with an Oops. Use the open_mutex to protect for it.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The pm_qos_request isn't freed properly when OSS PCM emulation is used
because it skips snd_pcm_hw_free() call but directly releases the
stream. This resulted in Oops later.
Tested-by: Simon Kirby <sim@hostway.ca>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
* git://git.kernel.org/pub/scm/linux/kernel/git/wim/linux-2.6-watchdog:
watchdog: Enable NXP LPC32XX support in Kconfig (resend)
watchdog: ts72xx_wdt: disable watchdog at probe
watchdog: sb_wdog: release irq and reboot notifier in error path and module_exit()
* 'stable' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
arch/tile: fix formatting bug in register dumps
arch/tile: fix memcpy_fromio()/memcpy_toio() signatures
arch/tile: Save and restore extra user state for tilegx
arch/tile: Change struct sigcontext to be more useful
arch/tile: finish const-ifying sys_execve()
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lrg/voltage-2.6:
regulator: wm8350-regulator - fix the logic of checking REGULATOR_MODE_STANDBY mode
regulator: wm831x-ldo - fix the logic to set REGULATOR_MODE_IDLE and REGULATOR_MODE_STANDBY modes
regulator: ab8500 - fix off-by-one value range checking for selector
regulator: 88pm8607 - fix value range checking for accessing info->vol_table
regulator: isl6271a-regulator - fix regulator_desc parameter for regulator_register()
regulator: ad5398 - fix a memory leak
regulator: Update e-mail address for Liam Girdwood
regulator: set max8998->dev to &pdev->dev.
regulator: tps6586x-regulator - fix bit_mask parameter for tps6586x_set_bits()
regulator: tps6586x-regulator - fix value range checking for val
regulator: max8998 - set max8998->num_regulators
regulator: max8998 - fix memory allocation size for max8998->rdev
regulator: tps6507x - remove incorrect comments
regulator: max1586 - improve the logic of choosing selector
regulator: ab8500 - fix the logic to remove already registered regulators in error path
regulator: ab3100 - fix the logic to remove already registered regulators in error path
regulator/ab8500: move dereference below the check for NULL
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
drm/radeon/kms: only warn on mipmap size checks in r600 cs checker (v2)
drm/radeon/kms: force legacy pll algo for RV620 LVDS
drm: fix race between driver loading and userspace open.
drm: Use a nondestructive mode for output detect when polling (v2)
drm/radeon/kms: fix the colorbuffer CS checker for r300-r500
drm/radeon/kms: increase lockup detection interval to 10 sec for r100-r500
drm/radeon/kms/evergreen: fix backend setup
drm: Use a nondestructive mode for output detect when polling
drm/radeon: add some missing copyright headers
drm: Only decouple the old_fb from the crtc is we call mode_set*
drm/radeon/kms: don't enable underscan with interlaced modes
drm/radeon/kms: add connector table for Mac x800
drm/radeon/kms: fix regression in RMX code (v2)
drm: Fix regression in disable polling e58f637
This patch adds CPU type detection for the Intel Celeron 540, which is
part of the Core 2 family according to Wikipedia; the family and ID pair
is absent from the Volume 3B table referenced in the source code
comments. I have tested this patch on an Intel Celeron 540 machine
reporting itself as Family 6 Model 22, and OProfile runs on the machine
without issue.
Spec:
http://download.intel.com/design/mobile/SPECUPDT/317667.pdf
Signed-off-by: Patrick Simmons <linuxrocks123@netscape.net>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: stable@kernel.org
Signed-off-by: Robert Richter <robert.richter@amd.com>
BugLink: http://launchpad.net/bugs/640254
In some cases a magic processing coefficient is needed to enable
the internal speaker on Dell M101z. According to Realtek, this
processing coefficient is only present on ALC269vb.
Cc: stable@kernel.org
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The Thinkpad X100e seems to have some odd behaviour when the display is
powered off - the onboard r8169 starts generating rxfifo overflow errors.
The root cause of this has not yet been identified and may well be a
hardware design bug on the platform, but r8169 should be more resiliant to
this. This patch enables the rxfifo interrupt on 8168 devices and removes
the MAC version check in the interrupt handler, and the machine no longer
crashes when under network load while the screen turns off.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The VIAFB_GET_INFO device ioctl allows unprivileged users to read 246
bytes of uninitialized stack memory, because the "reserved" member of
the viafb_ioctl_info struct declared on the stack is not altered or
zeroed before being copied back to the user. This patch takes care of
it.
Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Tony's fix (f574c84319) has a small bug,
it incorrectly uses "r3" as a scratch register in the first of the two
unlock paths ... it is also inefficient. Optimize the fast path again.
Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Tony Luck <tony.luck@intel.com>
If peer uses tiny MSS (say, 75 bytes) and similarly tiny advertised
window, the SWS logic will packetize to half the MSS unnecessarily.
This causes problems with some embedded devices.
However for large MSS devices we do want to half-MSS packetize
otherwise we never get enough packets into the pipe for things
like fast retransmit and recovery to work.
Be careful also to handle the case where MSS > window, otherwise
we'll never send until the probe timer.
Reported-by: ツ Leandro Melo de Sales <leandroal@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The NXP LPC32XX processor use the same watchdog as the Philips
PNX4008 processor.
Signed-off-by: Kevin Wells <wellsk40@gmail.com>
Tested-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Since it may be already enabled by bootloader or some other utility. This patch
makes sure that the watchdog is disabled before any userspace daemon opens the
device. It is also required by the watchdog API.
Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
irq and reboot notifier are acquired in module_init() but never released.
They should be released correctly, otherwise reloading the module or error
during module_init() will cause a problem.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Andrew Sharp <andy.sharp@lsi.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Some pcnet_cs compatible cards require an exact 16-lines match
of the ioport areas specified in CIS, but set the "iolines"
value in the CIS incorrectly. We can easily work around this
issue -- same as we do in serial_cs -- by first trying setting
iolines to the CIS-specified value, and then trying a 16-line
match.
Reported-and-tested-by: Wolfram Sang <w.sang@pengutronix.de>
Hardware-supplied-by: Jochen Frieling <j.frieling@pengutronix.de>
CC: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
As the iomem / ioport setup differs per device, it is much better
to print out the device instead of the socket.
Tested-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
We shouldn't overwrite pre-set values, and we should also
set the port address to the beginning, and not the end of
the 8-port range.
CC: linux-serial@vger.kernel.org
Reported-by: Komuro <komurojun-mbn@nifty.com>
Hardware-supplied-by: Jochen Frieling <j.frieling@pengutronix.de>
Tested-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
This cut-and-paste bug was caused by rewriting the register dump
code to use only a single printk per line of output.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
During context switch, save and restore a couple of additional bits of
tilegx user state that can be persistently modified by userspace.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Rather than just using pt_regs, it now contains the actual saved
state explicitly, similar to pt_regs. By doing it this way, we
provide a cleaner API for userspace (or equivalently, we avoid the
need for libc to provide its own definition of sigcontext).
While we're at it, move PT_FLAGS_xxx to where they are not visible
from userspace. And always pass siginfo and mcontext to signal
handlers, even if they claim they don't need it, since sometimes
they actually try to use it anyway in practice.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
The sys_execve() implementation was properly const-ified but not
the declaration, the syscall wrappers, or the compat version.
This change completes the constification process.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
We have 32-bit variable overflow possibility when multiply in
task_times() and thread_group_times() functions. When the
overflow happens then the scaled utime value becomes erroneously
small and the scaled stime becomes i erroneously big.
Reported here:
https://bugzilla.redhat.com/show_bug.cgi?id=633037https://bugzilla.kernel.org/show_bug.cgi?id=16559
Reported-by: Michael Chapman <redhat-bugzilla@very.puzzling.org>
Reported-by: Ciriaco Garcia de Celis <sysman@etherpilot.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: <stable@kernel.org> # 2.6.32.19+ (partially) and 2.6.33+
LKML-Reference: <20100914143513.GB8415@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
You cannot invoke __smp_call_function_single() unless the
architecture sets this symbol.
Reported-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The texture base address registers are in units of 256 bytes.
The original CS checker treated these offsets as bytes, so the
original check was wrong. I fixed the units in a patch during
the 2.6.36 cycle, but this ended up breaking some existing
userspace (probably due to a bug in either userspace texture allocation
or the drm texture mipmap checker). So for now, until we come
up with a better fix, just warn if the mipmap size it too large.
This will keep existing userspace working and it should be just
as safe as before when we were checking the wrong units. These
are GPU MC addresses, so if they fall outside of the VRAM or
GART apertures, they end up at the GPU default page, so this should
be safe from a security perspective.
v2: Just disable the warning. It just spams the log and there's
nothing the user can do about it.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: Jerome Glisse <glisse@freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
* ssh://master.kernel.org/home/hpa/tree/sec:
x86-64, compat: Retruncate rax after ia32 syscall entry tracing
x86-64, compat: Test %rax for the syscall number, not %eax
compat: Make compat_alloc_user_space() incorporate the access_ok()
Fix up the IRQ names for the MN10300 on-chip serial ports in the driver as
request_interrupt() no longer allows names containing slashes, giving a warning
like the following if one is encountered:
------------[ cut here ]------------
WARNING: at fs/proc/generic.c:323 __xlate_proc_name+0x62/0x7c()
name 'ttySM0/Rx'
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.infradead.org/mtd-2.6:
mtd: pxa3xx: fix build error when CONFIG_MTD_PARTITIONS is not defined
mtd: mxc_nand: configure pages per block for v2 controller
mtd: OneNAND: Fix loop hang when DMA error at Samsung SoCs
mtd: OneNAND: Fix 2KiB pagesize handling at Samsung SoCs
mtd: Blackfin NFC: fix invalid free in remove()
mtd: Blackfin NFC: fix build error after nand_scan_ident() change
mxc_nand: Do not do byte accesses to the NFC buffer.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
HID: fix hiddev's use of usb_find_interface
HID: fixup blacklist entry for Asus T91MT
HID: add device ID for new Asus Multitouch Controller
HID: add no-get quirk for eGalax touch controller
HID: Add quirk for eGalax touch controler.
HID: add support for another BTC Emprex remote control
HID: Set Report ID properly for Output reports on the Control endpoint.
HID: Kanvus Note A5 tablet needs HID_QUIRK_MULTI_INPUT
HID: Add support for chicony multitouch screens.
* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6:
SUNRPC: Fix the NFSv4 and RPCSEC_GSS Kconfig dependencies
statfs() gives ESTALE error
NFS: Fix a typo in nfs_sockaddr_match_ipaddr6
sunrpc: increase MAX_HASHTABLE_BITS to 14
gss:spkm3 miss returning error to caller when import security context
gss:krb5 miss returning error to caller when import security context
Remove incorrect do_vfs_lock message
SUNRPC: cleanup state-machine ordering
SUNRPC: Fix a race in rpc_info_open
SUNRPC: Fix race corrupting rpc upcall
Fix null dereference in call_allocate
Tavis Ormandy pointed out that do_io_submit does not do proper bounds
checking on the passed-in iocb array:
if (unlikely(nr < 0))
return -EINVAL;
if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(iocbpp)))))
return -EFAULT; ^^^^^^^^^^^^^^^^^^
The attached patch checks for overflow, and if it is detected, the
number of iocbs submitted is scaled down to a number that will fit in
the long. This is an ok thing to do, as sys_io_submit is documented as
returning the number of iocbs submitted, so callers should handle a
return value of less than the 'nr' argument passed in.
Reported-by: Tavis Ormandy <taviso@cmpxchg8b.com>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cifs_get_smb_ses must be called on a server pointer on which it holds an
active reference. It first does a search for an existing SMB session. If
it finds one, it'll put the server reference and then try to ensure that
the negprot is done, etc.
If it encounters an error at that point then it'll return an error.
There's a potential problem here though. When cifs_get_smb_ses returns
an error, the caller will also put the TCP server reference leading to a
double-put.
Fix this by having cifs_get_smb_ses only put the server reference if
it found an existing session that it could use and isn't returning an
error.
Cc: stable@kernel.org
Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
In commit d4d6715, we reopened an old hole for a 64-bit ptracer touching a
32-bit tracee in system call entry. A %rax value set via ptrace at the
entry tracing stop gets used whole as a 32-bit syscall number, while we
only check the low 32 bits for validity.
Fix it by truncating %rax back to 32 bits after syscall_trace_enter,
in addition to testing the full 64 bits as has already been added.
Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
On 64 bits, we always, by necessity, jump through the system call
table via %rax. For 32-bit system calls, in theory the system call
number is stored in %eax, and the code was testing %eax for a valid
system call number. At one point we loaded the stored value back from
the stack to enforce zero-extension, but that was removed in checkin
d4d6715016. An actual 32-bit process
will not be able to introduce a non-zero-extended number, but it can
happen via ptrace.
Instead of re-introducing the zero-extension, test what we are
actually going to use, i.e. %rax. This only adds a handful of REX
prefixes to the code.
Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@kernel.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
compat_alloc_user_space() expects the caller to independently call
access_ok() to verify the returned area. A missing call could
introduce problems on some architectures.
This patch incorporates the access_ok() check into
compat_alloc_user_space() and also adds a sanity check on the length.
The existing compat_alloc_user_space() implementations are renamed
arch_compat_alloc_user_space() and are used as part of the
implementation of the new global function.
This patch assumes NULL will cause __get_user()/__put_user() to either
fail or access userspace on all architectures. This should be
followed by checking the return value of compat_access_user_space()
for NULL in the callers, at which time the access_ok() in the callers
can also be removed.
Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <jejb@parisc-linux.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: <stable@kernel.org>
This more or less reverts commits 08be979 (x86: Force HPET
readback_cmp for all ATI chipsets) and 30a564be (x86, hpet: Restrict
read back to affected ATI chipsets) to the status of commit 8da854c
(x86, hpet: Erratum workaround for read after write of HPET
comparator).
The delta to commit 8da854c is mostly comments and the change from
WARN_ONCE to printk_once as we know the call path of this function
already.
This needs really in depth explanation:
First of all the HPET design is a complete failure. Having a counter
compare register which generates an interrupt on matching values
forces the software to do at least one superfluous readback of the
counter register.
While it is nice in theory to program "absolute" time events it is
practically useless because the timer runs at some absurd frequency
which can never be matched to real world units. So we are forced to
calculate a relative delta and this forces a readout of the actual
counter value, adding the delta and programming the compare
register. When the delta is small enough we run into the danger that
we program a compare value which is already in the past. Due to the
compare for equal nature of HPET we need to read back the counter
value after writing the compare rehgister (btw. this is necessary for
absolute timeouts as well) to make sure that we did not miss the timer
event. We try to work around that by setting the minimum delta to a
value which is larger than the theoretical time which elapses between
the counter readout and the compare register write, but that's only
true in theory. A NMI or SMI which hits between the readout and the
write can easily push us beyond that limit. This would result in
waiting for the next HPET timer interrupt until the 32bit wraparound
of the counter happens which takes about 306 seconds.
So we designed the next event function to look like:
match = read_cnt() + delta;
write_compare_ref(match);
return read_cnt() < match ? 0 : -ETIME;
At some point we got into trouble with certain ATI chipsets. Even the
above "safe" procedure failed. The reason was that the write to the
compare register was delayed probably for performance reasons. The
theory was that they wanted to avoid the synchronization of the write
with the HPET clock, which is understandable. So the write does not
hit the compare register directly instead it goes to some intermediate
register which is copied to the real compare register in sync with the
HPET clock. That opens another window for hitting the dreaded "wait
for a wraparound" problem.
To work around that "optimization" we added a read back of the compare
register which either enforced the update of the just written value or
just delayed the readout of the counter enough to avoid the issue. We
unfortunately never got any affirmative info from ATI/AMD about this.
One thing is sure, that we nuked the performance "optimization" that
way completely and I'm pretty sure that the result is worse than
before some HW folks came up with those.
Just for paranoia reasons I added a check whether the read back
compare register value was the same as the value we wrote right
before. That paranoia check triggered a couple of years after it was
added on an Intel ICH9 chipset. Venki added a workaround (commit
8da854c) which was reading the compare register twice when the first
check failed. We considered this to be a penalty in general and
restricted the readback (thus the wasted CPU cycles) to the known to
be affected ATI chipsets.
This turned out to be a utterly wrong decision. 2.6.35 testers
experienced massive problems and finally one of them bisected it down
to commit 30a564be which spured some further investigation.
Finally we got confirmation that the write to the compare register can
be delayed by up to two HPET clock cycles which explains the problems
nicely. All we can do about this is to go back to Venki's initial
workaround in a slightly modified version.
Just for the record I need to say, that all of this could have been
avoided if hardware designers and of course the HPET committee would
have thought about the consequences for a split second. It's out of my
comprehension why designing a working timer is so hard. There are two
ways to achieve it:
1) Use a counter wrap around aware compare_reg <= counter_reg
implementation instead of the easy compare_reg == counter_reg
Downsides:
- It needs more silicon.
- It needs a readout of the counter to apply a relative
timeout. This is necessary as the counter does not run in
any useful (and adjustable) frequency and there is no
guarantee that the counter which is used for timer events is
the same which is used for reading the actual time (and
therefor for calculating the delta)
Upsides:
- None
2) Use a simple down counter for relative timer events
Downsides:
- Absolute timeouts are not possible, which is not a problem
at all in the context of an OS and the expected
max. latencies/jitter (also see Downsides of #1)
Upsides:
- It needs less or equal silicon.
- It works ALWAYS
- It is way faster than a compare register based solution (One
write versus one write plus at least one and up to four
reads)
I would not be so grumpy about all of this, if I would not have been
ignored for many years when pointing out these flaws to various
hardware folks. I really hate timers (at least those which seem to be
designed by janitors).
Though finally we got a reasonable explanation plus a solution and I
want to thank all the folks involved in chasing it down and providing
valuable input to this.
Bisected-by: Nix <nix@esperi.org.uk>
Reported-by: Artur Skawina <art.08.09@gmail.com>
Reported-by: Damien Wyart <damien.wyart@free.fr>
Reported-by: John Drescher <drescherjm@gmail.com>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Cc: stable@kernel.org
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Stop sending FLUSHSNAP messages when we hit a capsnap that has dirty_pages
or is still writing. We'll send the newer capsnaps only after the older
ones complete.
Signed-off-by: Sage Weil <sage@newdream.net>
The 'follows' should match the seq for the snap context for the given snap
cap, which is the context under which we have been dirtying and writing
data and metadata. The snapshot that _contains_ those updates thus
_follows_ that context's seq #.
Signed-off-by: Sage Weil <sage@newdream.net>
