Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add way to quickly start stop tracing from the kernel
This patch adds a soft stop and start to the trace. This simply
disables function tracing via the ftrace_disabled flag, and
disables the trace buffers to prevent recording. The tracing
code may still be executed, but the trace will not be recorded.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: quick start and stop of function tracer
This patch adds a way to disable the function tracer quickly without
the need to run kstop_machine. It adds a new variable called
function_trace_stop which will stop the calls to functions from mcount
when set. This is just an on/off switch and does not handle recursion
like preempt_disable().
It's main purpose is to help other tracers/debuggers start and stop tracing
fuctions without the need to call kstop_machine.
The config option HAVE_FUNCTION_TRACE_MCOUNT_TEST is added for archs
that implement the testing of the function_trace_stop in the mcount
arch dependent code. Otherwise, the test is done in the C code.
x86 is the only arch at the moment that supports this.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix boot tracer + sched tracer coupling bug
Fix a bug that made the sched_switch tracer unable to run
if set as the current_tracer after the boot tracer.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
This patch applies some corrections suggested by Steven Rostedt.
Change the type of shed_ref into int since it is used
into a Mutex, we don't need it anymore as an atomic
variable in the sched_switch tracer.
Also change the name of the register mutex.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: enhance boot trace output with scheduling events
Use the sched_switch tracer from the boot tracer.
We also can trace schedule events inside the initcalls.
Sched tracing is disabled after the initcall has finished and
then reenabled before the next one is started.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
When init_sched_switch_trace() is called, it has no reason to start
the sched tracer if the sched_ref is not zero.
_ If this is non-zero, the tracer is already used, but we can register it
to the tracing engine. There is already a security which avoid the tracer
probes not to be resgistered twice.
_ If this is zero, this block will not be used.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix race condition in sched_switch tracer
This patch fixes a race condition in the sched_switch tracer. If
several tasks (IE: concurrent initcalls) are playing with
tracing_start_cmdline_record() and tracing_stop_cmdline_record(), the
following situation could happen:
_ Task A and B are using the same tracepoint probe. Task A holds it.
Task B is sleeping and doesn't hold it.
_ Task A frees the sched tracer, then sched_ref is decremented to 0.
_ Task A is preempted and hadn't yet unregistered its tracepoint
probe, then B runs.
_ B increments sched_ref, sees it's 1 and then guess it has to
register its probe. But it has not been freed by task A.
_ A lot of bad things can happen after that...
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: modify boot tracer
We used to disable the initcall tracing at a specified time (IE: end
of builtin initcalls). But we don't need it anymore. It will be
stopped when initcalls are finished.
However we want two things:
_Start this tracing only after pre-smp initcalls are finished.
_Since we are planning to trace sched_switches at the same time, we
want to enable them only during the initcall execution.
For this purpose, this patch introduce two functions to enable/disable
the sched_switch tracing during boot.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix sysctl name typo
Steve must have needed more coffee ;-)
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add SysRq-z support to dump trace buffers
Allows one to force an ftrace dump from sysrq
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: disable interrupts during trace entry creation (as opposed to preempt)
To help with performance, I set the ftracer to not disable interrupts,
and only to disable preemption. If an interrupt occurred, it would not
be traced, because the function tracer protects itself from recursion.
This may be faster, but the trace output might miss some traces.
This patch makes the fuction trace disable interrupts, but it also
adds a runtime feature to disable preemption instead. It does this by
having two different tracer functions. When the function tracer is
enabled, it will check to see which version is requested (irqs disabled
or preemption disabled). Then it will use the corresponding function
as the tracer.
Irq disabling is the default behaviour, but if the user wants better
performance, with the chance of missing traces, then they can choose
the preempt disabled version.
Running hackbench 3 times with the irqs disabled and 3 times with
the preempt disabled function tracer yielded:
tracing type times entries recorded
------------ -------- ----------------
irq disabled 43.393 166433066
43.282 166172618
43.298 166256704
preempt disabled 38.969 159871710
38.943 159972935
39.325 161056510
Average:
irqs disabled: 43.324 166287462
preempt disabled: 39.079 160300385
preempt is 10.8 percent faster than irqs disabled.
I wrote a patch to count function trace recursion and reran hackbench.
With irq disabled: 1,150 times the function tracer did not trace due to
recursion.
with preempt disabled: 5,117,718 times.
The thousand times with irq disabled could be due to NMIs, or simply a case
where it called a function that was not protected by notrace.
But we also see that a large amount of the trace is lost with the
preempt version.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: use new, consolidated APIs in ftrace plugins
This patch replaces the schedule safe preempt disable code with the
ftrace_preempt_disable() and ftrace_preempt_enable() safe functions.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add new ftrace-plugin internal APIs
Parts of the tracer needs to be careful about schedule recursion.
If the NEED_RESCHED flag is set, a preempt_enable will call schedule.
Inside the schedule function, the NEED_RESCHED flag is cleared.
The problem arises when a trace happens in the schedule function but before
NEED_RESCHED is cleared. The race is as follows:
schedule()
>> tracer called
trace_function()
preempt_disable()
[ record trace ]
preempt_enable() <<- here's the issue.
[check NEED_RESCHED]
schedule()
[ Repeat the above, over and over again ]
The naive approach is simply to use preempt_enable_no_schedule instead.
The problem with that approach is that, although we solve the schedule
recursion issue, we now might lose a preemption check when not in the
schedule function.
trace_function()
preempt_disable()
[ record trace ]
[Interrupt comes in and sets NEED_RESCHED]
preempt_enable_no_resched()
[continue without scheduling]
The way ftrace handles this problem is with the following approach:
int resched;
resched = need_resched();
preempt_disable_notrace();
[record trace]
if (resched)
preempt_enable_no_sched_notrace();
else
preempt_enable_notrace();
This may seem like the opposite of what we want. If resched is set
then we call the "no_sched" version?? The reason we do this is because
if NEED_RESCHED is set before we disable preemption, there's two reasons
for that:
1) we are in an atomic code path
2) we are already on our way to the schedule function, and maybe even
in the schedule function, but have yet to clear the flag.
Both the above cases we do not want to schedule.
This solution has already been implemented within the ftrace infrastructure.
But the problem is that it has been implemented several times. This patch
encapsulates this code to two nice functions.
resched = ftrace_preempt_disable();
[ record trace]
ftrace_preempt_enable(resched);
This way the tracers do not need to worry about getting it right.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add new tracepoint APIs to allow the batched registration of probes
new APIs separate tracepoint_probe_register(),
tracepoint_probe_unregister() into 2 steps. The first step of them
is just update tracepoint_entry, not connect or disconnect.
this patch introduces tracepoint_probe_update_all() for update all.
these APIs are very useful for registering lots of probes
but just updating once. Another very important thing is that
*_noupdate APIs do not require module_mutex.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: simplify implementation
Now, unused memory is handled by struct tp_probes.
old code use these three field to handle unused memory.
struct tracepoint_entry {
...
struct rcu_head rcu;
void *oldptr;
unsigned char rcu_pending:1;
...
};
in this way, unused memory is handled by struct tracepoint_entry.
it bring reenter bug(it was fixed) and tracepoint.c is filled
full of ".*rcu.*" code statements. this patch removes all these.
and:
rcu_barrier_sched() is removed.
Do not need regain tracepoints_mutex after tracepoint_update_probes()
several little cleanup.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix on !stacktrace architectures
only select STACKTRACE on architectures that have STACKTRACE_SUPPORT
... since we also need to ifdef out the guts of ftrace_trace_stack().
We also want to disallow setting TRACE_ITER_STACKTRACE in trace_flags
on such configs, but that can wait.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add new (optional) debug boot option
In order to facilitate early boot trouble, allow one to specify a tracer
on the kernel boot line.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6:
ide-gd: re-get capacity on revalidate
tx4938ide: Avoid underflow on calculation of a wait cycle
tx4938ide: Do not call devm_ioremap for whole 128KB
tx4938ide: Check minimum cycle time and SHWT range (v2)
ide: Switch to a common address
ide-cd: fix DMA alignment regression
We need to re-get a removable media's capacity when revalidating the
disk so that its partitions get rescanned by the block layer.
Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: axboe@kernel.dk
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Make 'wt' variable signed while it can be negative during calculation.
Suggested-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: sshtylyov@ru.mvista.com
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Call devm_ioremap() for CS0 and CS1 separetely.
And some style cleanups.
Suggested-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: ralf@linux-mips.org
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
SHWT value is used as address valid to -CSx assertion and -CSx to -DIOx
assertion setup time, and contrarywise, -DIOx to -CSx release and -CSx
release to address invalid hold time, so it actualy applies 4 times and
so constitutes -DIOx recovery time. Check requirement of the recovery
time and cycle time. Also check SHWT maximum value.
Suggested-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: ralf@linux-mips.org
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
e5318b531b ("ide: use the dma safe check for
REQ_TYPE_ATA_PC") introduced a regression which caused some ATAPI drives to
turn off DMA for REQ_TYPE_BLOCK_PC commands while burning and thus degrading
performance and ultimately causing an excessive amount of underruns.
The issue is documented also in:
http://bugzilla.kernel.org/show_bug.cgi?id=11742.
Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Tested-by: Valerio Passini <valerio.passini@unicam.it>
[bart: fixup patch description per comments from Sergei Shtylyov]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (33 commits)
af_unix: netns: fix problem of return value
IRDA: remove double inclusion of module.h
udp: multicast packets need to check namespace
net: add documentation for skb recycling
key: fix setkey(8) policy set breakage
bpa10x: free sk_buff with kfree_skb
xfrm: do not leak ESRCH to user space
net: Really remove all of LOOPBACK_TSO code.
netfilter: nf_conntrack_proto_gre: switch to register_pernet_gen_subsys()
netns: add register_pernet_gen_subsys/unregister_pernet_gen_subsys
net: delete excess kernel-doc notation
pppoe: Fix socket leak.
gianfar: Don't reset TBI<->SerDes link if it's already up
gianfar: Fix race in TBI/SerDes configuration
at91_ether: request/free GPIO for PHY interrupt
amd8111e: fix dma_free_coherent context
atl1: fix vlan tag regression
SMC91x: delete unused local variable "lp"
myri10ge: fix stop/go mmio ordering
bonding: fix panic when taking bond interface down before removing module
...
There is a problem discovered in recent versions of ATI Mach64 driver
in X.org on sparc64 architecture. In short, the driver fails to mmap
MMIO aperture (PCI resource #2).
I've found that kernel's __pci_mmap_make_offset() returns EINVAL. It
checks whether user attempts to mmap more than the resource length,
which is 0x1000 bytes in our case. But PAGE_SIZE on SPARC64 is 0x2000
and this is what actually is being mmaped. So __pci_mmap_make_offset()
failed for this PCI resource.
Signed-off-by: Max Dmitrichenko <dmitrmax@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
GCC warns because some tests against 32-bit values never evaluate to
true due to how TASK_SIZE is defined.
I always wanted to mimick powerpc's definition of TASK_SIZE, which
is simply TASK_SIZE_OF(current) and that also fixes the warning.
Signed-off-by: David S. Miller <davem@davemloft.net>
Alexander Beregalov reports oops in __bzero() called from
copy_from_user_fixup() called from iov_iter_copy_from_user_atomic(),
when running dbench on tmpfs on sparc64: its __copy_from_user_inatomic
and __copy_to_user_inatomic should be avoiding, not calling, the fixups.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
fix problem of return value
net/unix/af_unix.c: unix_net_init()
when error appears, it should return 'error', not always return 0.
Signed-off-by: Jianjun Kong <jianjun@zeuux.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Current UDP multicast delivery is not namespace aware.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 04a4bb55bc ("net: add
skb_recycle_check() to enable netdriver skb recycling") added a
method for network drivers to recycle skbuffs, but while use of
this mechanism was documented in the commit message, it should
really have been added as a docbook comment as well -- this
patch does that.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
cirrusfb_zorro_unmap() may be called both from __devexit and (on
cleanup path) from __devinit. So it needs to be a normal function,
same as for cirrusfb_pci_unmap()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Insufficient dependency - we really want CONFIG_RTC_CLASS=y there.
That will give us CONFIG_RTC_LIB=y, so the old dependency can be
simply replaced.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We broke O_NONBLOCK handling in OSS dmasound_core in 2.3.11-pre3 - the
original code copied f_flags to open_mode and then checked for
O_NONBLOCK in there, but that got changed to copying f_mode and
O_NONBLOCK has not reached that field in any kernel version.
Since we do not care for any other bits, the fix is obvious...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: fix AMDC1E and XTOPOLOGY conflict in cpufeature
x86: build fix
Removed duplicated #include <linux/delay.h> in init/do_mounts_md.c.
The same compile error ("error: implicit declaration of function
'msleep'") got fixed twice:
- f8b77d3939 ("init/do_mounts_md.c:
msleep compile fix")
- 73b4a24f5f ("init/do_mounts_md.c must
#include <linux/delay.h>")
by people adding the <linux/delay.h> include in two slightly different
places. Andrew's quilt scripts happily ignore the fuzz, and will
re-apply the patch even though they had conflicts.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes the late e820 resources use 'insert_resource_expand_to_fit()'
instead of doing a 'reserve_region_with_split()', and also avoids
marking them as IORESOURCE_BUSY.
This results in us being perfectly happy to use pre-existing PCI
resources even if they were marked as being in a reserved region, while
still avoiding any _new_ allocations in the reserved regions. It also
makes for a simpler and more accurate resource tree.
Example resource allocation from Jonathan Corbet, who has firmware that
has an e820 reserved entry that covered a big range (e0000000-fed003ff),
and that had various PCI resources in it set up by firmware.
With old kernels, the reserved range would force us to re-allocate all
pre-existing PCI resources, and his reserved range would end up looking
like this:
e0000000-fed003ff : reserved
fec00000-fec00fff : IOAPIC 0
fed00000-fed003ff : HPET 0
where only the pre-allocated special regions (IOAPIC and HPET) were kept
around.
With 2.6.28-rc2, which uses 'reserve_region_with_split()', Jonathan's
resource tree looked like this:
e0000000-fe7fffff : reserved
fe800000-fe8fffff : PCI Bus 0000:01
fe800000-fe8fffff : reserved
fe900000-fe9d9aff : reserved
fe9d9b00-fe9d9bff : 0000:00:1f.3
fe9d9b00-fe9d9bff : reserved
fe9d9c00-fe9d9fff : 0000:00:1a.7
fe9d9c00-fe9d9fff : reserved
fe9da000-fe9dafff : 0000:00:03.3
fe9da000-fe9dafff : reserved
fe9db000-fe9dbfff : 0000:00:19.0
fe9db000-fe9dbfff : reserved
fe9dc000-fe9dffff : 0000:00:1b.0
fe9dc000-fe9dffff : reserved
fe9e0000-fe9fffff : 0000:00:19.0
fe9e0000-fe9fffff : reserved
fea00000-fea7ffff : 0000:00:02.0
fea00000-fea7ffff : reserved
fea80000-feafffff : 0000:00:02.1
fea80000-feafffff : reserved
feb00000-febfffff : 0000:00:02.0
feb00000-febfffff : reserved
fec00000-fed003ff : reserved
fec00000-fec00fff : IOAPIC 0
fed00000-fed003ff : HPET 0
and because the reserved entry had been split and moved into the
individual resources, and because it used the IORESOURCE_BUSY flag, the
drivers that actually wanted to _use_ those resources couldn't actually
attach to them:
e1000e 0000:00:19.0: BAR 0: can't reserve mem region [0xfe9e0000-0xfe9fffff]
HDA Intel 0000:00:1b.0: BAR 0: can't reserve mem region [0xfe9dc000-0xfe9dffff]
with this patch, the resource tree instead becomes
e0000000-fed003ff : reserved
fe800000-fe8fffff : PCI Bus 0000:01
fe9d9b00-fe9d9bff : 0000:00:1f.3
fe9d9c00-fe9d9fff : 0000:00:1a.7
fe9d9c00-fe9d9fff : ehci_hcd
fe9da000-fe9dafff : 0000:00:03.3
fe9db000-fe9dbfff : 0000:00:19.0
fe9db000-fe9dbfff : e1000e
fe9dc000-fe9dffff : 0000:00:1b.0
fe9dc000-fe9dffff : ICH HD audio
fe9e0000-fe9fffff : 0000:00:19.0
fe9e0000-fe9fffff : e1000e
fea00000-fea7ffff : 0000:00:02.0
fea80000-feafffff : 0000:00:02.1
feb00000-febfffff : 0000:00:02.0
fec00000-fec00fff : IOAPIC 0
fed00000-fed003ff : HPET 0
ie the one reserved region now ends up surrounding all the PCI resources
that were allocated inside of it by firmware, and because it is not
marked BUSY, drivers have no problem attaching to the pre-allocated
resources.
Reported-and-tested-by: Jonathan Corbet <corbet@lwn.net>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This one apparently doesn't generate any warnings, because the function
is only used during system bootup, when the warnings are disabled. But
it's still very wrong.
The __reserve_region_with_split() function is called with the
resource_lock held for writing, so it must only ever do GFP_ATOMIC
allocations.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
