irq: remove unused flags argument from __handle_irq_event_percpu()

The __IRQF_TIMER bit from the flags argument was used in
add_interrupt_randomness() to distinguish the timer interrupt from other
i

irq: remove unused flags argument from __handle_irq_event_percpu()

The __IRQF_TIMER bit from the flags argument was used in
add_interrupt_randomness() to distinguish the timer interrupt from other
interrupts. This is no longer the case.

Remove the flags argument from __handle_irq_event_percpu().

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>

show more ...

random: remove unused irq_flags argument from add_interrupt_randomness()

Since commit
ee3e00e9e7101 ("random: use registers from interrupted code for CPU's w/o a cycle counter")

the irq_flags ar

random: remove unused irq_flags argument from add_interrupt_randomness()

Since commit
ee3e00e9e7101 ("random: use registers from interrupted code for CPU's w/o a cycle counter")

the irq_flags argument is no longer used.

Remove unused irq_flags.

Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dexuan Cui <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: K. Y. Srinivasan <[email protected]>
Cc: Stephen Hemminger <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Wei Liu <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Acked-by: Wei Liu <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>

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irq: add generic_handle_arch_irq()

Several architectures select GENERIC_IRQ_MULTI_HANDLER and branch to
handle_arch_irq() without performing any entry accounting.

Add a generic wrapper to handle th

irq: add generic_handle_arch_irq()

Several architectures select GENERIC_IRQ_MULTI_HANDLER and branch to
handle_arch_irq() without performing any entry accounting.

Add a generic wrapper to handle the common irqentry work when invoking
handle_arch_irq(). Where an architecture needs to perform some entry
accounting itself, it will need to invoke handle_arch_irq() itself.

In subsequent patches it will become the responsibilty of the entry code
to set the irq regs when entering an IRQ (rather than deferring this to
an irqchip handler), so generic_handle_arch_irq() is made to set the irq
regs now. This can be redundant in some cases, but is never harmful as
saving/restoring the old regs nests safely.

Signed-off-by: Mark Rutland <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Reviewed-by: Guo Ren <[email protected]>
Cc: Thomas Gleixner <[email protected]>

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genirq: Add a IRQF_NO_DEBUG flag

The whole call to note_interrupt() can be avoided or return early when
interrupts would be marked accordingly. For IPI handlers which always
return HANDLED the whole

genirq: Add a IRQF_NO_DEBUG flag

The whole call to note_interrupt() can be avoided or return early when
interrupts would be marked accordingly. For IPI handlers which always
return HANDLED the whole procedure is pretty pointless to begin with.

Add a IRQF_NO_DEBUG flag and mark the interrupt accordingly if supplied
when the interrupt is requested.

When noirqdebug is set on the kernel commandline, then the interrupt is
marked unconditionally so that there is only one condition in the hotpath
to evaluate.

[ clg: Add changelog ]

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Cédric Le Goater <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through mar

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <[email protected]>

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lockdep: Introduce wait-type checks

Extend lockdep to validate lock wait-type context.

The current wait-types are:

LD_WAIT_FREE, /* wait free, rcu etc.. */
LD_WAIT_SPIN, /* spin loops, raw_spi

lockdep: Introduce wait-type checks

Extend lockdep to validate lock wait-type context.

The current wait-types are:

LD_WAIT_FREE, /* wait free, rcu etc.. */
LD_WAIT_SPIN, /* spin loops, raw_spinlock_t etc.. */
LD_WAIT_CONFIG, /* CONFIG_PREEMPT_LOCK, spinlock_t etc.. */
LD_WAIT_SLEEP, /* sleeping locks, mutex_t etc.. */

Where lockdep validates that the current lock (the one being acquired)
fits in the current wait-context (as generated by the held stack).

This ensures that there is no attempt to acquire mutexes while holding
spinlocks, to acquire spinlocks while holding raw_spinlocks and so on. In
other words, its a more fancy might_sleep().

Obviously RCU made the entire ordeal more complex than a simple single
value test because RCU can be acquired in (pretty much) any context and
while it presents a context to nested locks it is not the same as it
got acquired in.

Therefore its necessary to split the wait_type into two values, one
representing the acquire (outer) and one representing the nested context
(inner). For most 'normal' locks these two are the same.

[ To make static initialization easier we have the rule that:
.outer == INV means .outer == .inner; because INV == 0. ]

It further means that its required to find the minimal .inner of the held
stack to compare against the outer of the new lock; because while 'normal'
RCU presents a CONFIG type to nested locks, if it is taken while already
holding a SPIN type it obviously doesn't relax the rules.

Below is an example output generated by the trivial test code:

raw_spin_lock(&foo);
spin_lock(&bar);
spin_unlock(&bar);
raw_spin_unlock(&foo);

[ BUG: Invalid wait context ]
-----------------------------
swapper/0/1 is trying to lock:
ffffc90000013f20 (&bar){....}-{3:3}, at: kernel_init+0xdb/0x187
other info that might help us debug this:
1 lock held by swapper/0/1:
#0: ffffc90000013ee0 (&foo){+.+.}-{2:2}, at: kernel_init+0xd1/0x187

The way to read it is to look at the new -{n,m} part in the lock
description; -{3:3} for the attempted lock, and try and match that up to
the held locks, which in this case is the one: -{2,2}.

This tells that the acquiring lock requires a more relaxed environment than
presented by the lock stack.

Currently only the normal locks and RCU are converted, the rest of the
lockdep users defaults to .inner = INV which is ignored. More conversions
can be done when desired.

The check for spinlock_t nesting is not enabled by default. It's a separate
config option for now as there are known problems which are currently
addressed. The config option allows to identify these problems and to
verify that the solutions found are indeed solving them.

The config switch will be removed and the checks will permanently enabled
once the vast majority of issues has been addressed.

[ bigeasy: Move LD_WAIT_FREE,… out of CONFIG_LOCKDEP to avoid compile
failure with CONFIG_DEBUG_SPINLOCK + !CONFIG_LOCKDEP]
[ tglx: Add the config option ]

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively

%pF and %pf are functionally equivalent to %pS and %ps conversion
specifiers. The former are deprecated, therefore switch

treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively

%pF and %pf are functionally equivalent to %pS and %ps conversion
specifiers. The former are deprecated, therefore switch the current users
to use the preferred variant.

The changes have been produced by the following command:

git grep -l '%p[fF]' | grep -v '^\(tools\|Documentation\)/' | \
while read i; do perl -i -pe 's/%pf/%ps/g; s/%pF/%pS/g;' $i; done

And verifying the result.

Link: http://lkml.kernel.org/r/[email protected]
Cc: Andy Shevchenko <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Sakari Ailus <[email protected]>
Acked-by: David Sterba <[email protected]> (for btrfs)
Acked-by: Mike Rapoport <[email protected]> (for mm/memblock.c)
Acked-by: Bjorn Helgaas <[email protected]> (for drivers/pci)
Acked-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>

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genirq: Correctly annotate implicit fall through

There is a plan to build the kernel with -Wimplicit-fallthrough. The
fallthrough in __handle_irq_event_percpu() has a fallthrough annotation
which is

genirq: Correctly annotate implicit fall through

There is a plan to build the kernel with -Wimplicit-fallthrough. The
fallthrough in __handle_irq_event_percpu() has a fallthrough annotation
which is followed by an additional comment and is not recognized by GCC.

Separate the 'fall through' and the rest of the comment with a dash so the
regular expression used by GCC matches.

Signed-off-by: Mathieu Malaterre <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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genirq: Add missing SPDX identifiers

Add SPDX identifiers to files

- which contain an explicit license boiler plate or reference

- which do not contain a license reference and were not updated i

genirq: Add missing SPDX identifiers

Add SPDX identifiers to files

- which contain an explicit license boiler plate or reference

- which do not contain a license reference and were not updated in the
initial SPDX conversion because the license was deduced by the scanners
via EXPORT_SYMBOL_GPL as GPL2.0 only.

[ tglx: Moved adding identifiers from the patch which removes the
references/boilerplate ]

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Kate Stewart <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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genirq: Cleanup top of file comments

Remove pointless references to the file name itself and condense the
information so it wastes less space.

Signed-off-by: Thomas Gleixner <[email protected]>
Ac

genirq: Cleanup top of file comments

Remove pointless references to the file name itself and condense the
information so it wastes less space.

Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Marc Zyngier <[email protected]>
Cc: Kate Stewart <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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genirq: Add CONFIG_GENERIC_IRQ_MULTI_HANDLER

The arm multi irq handler registration mechanism has been copied into a
handful of architectures, including arm64 and openrisc. RISC-V needs the
same mec

genirq: Add CONFIG_GENERIC_IRQ_MULTI_HANDLER

The arm multi irq handler registration mechanism has been copied into a
handful of architectures, including arm64 and openrisc. RISC-V needs the
same mechanism.

Instead of adding yet another copy for RISC-V copy the arm implementation
into the core code depending on a new Kconfig symbol:
CONFIG_GENERIC_MULTI_IRQ_HANDLER.

Subsequent patches will convert the various architectures.

Signed-off-by: Palmer Dabbelt <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

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genirq/timings: Add infrastructure to track the interrupt timings

The interrupt framework gives a lot of information about each interrupt. It
does not keep track of when those interrupts occur thoug

genirq/timings: Add infrastructure to track the interrupt timings

The interrupt framework gives a lot of information about each interrupt. It
does not keep track of when those interrupts occur though, which is a
prerequisite for estimating the next interrupt arrival for power management
purposes.

Add a mechanism to record the timestamp for each interrupt occurrences in a
per-CPU circular buffer to help with the prediction of the next occurrence
using a statistical model.

Each CPU can store up to IRQ_TIMINGS_SIZE events <irq, timestamp>, the
current value of IRQ_TIMINGS_SIZE is 32.

Each event is encoded into a single u64, where the high 48 bits are used
for the timestamp and the low 16 bits are for the irq number.

A static key is introduced so when the irq prediction is switched off at
runtime, the overhead is near to zero.

It results in most of the code in internals.h for inline reasons and a very
few in the new file timings.c. The latter will contain more in the next patch
which will provide the statistical model for the next event prediction.

Signed-off-by: Daniel Lezcano <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Nicolas Pitre <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Vincent Guittot <[email protected]>
Cc: "Rafael J . Wysocki" <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]

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irq: update genericirq book location

This book got converted from DocBook. Update its references to
point to the current location.

Signed-off-by: Mauro Carvalho Chehab <[email protected]>

genirq: Add untracked irq handler

This adds a software irq handler for controllers that multiplex
interrupts from multiple devices, but don't know which device generated
the interrupt. For these dev

genirq: Add untracked irq handler

This adds a software irq handler for controllers that multiplex
interrupts from multiple devices, but don't know which device generated
the interrupt. For these devices, the irq handler that demuxes must
check every action for every software irq using the same h/w irq in order
to find out which device generated the interrupt. This will inevitably
trigger spurious interrupt detection if we are noting the irq.

The new irq handler does not track the handling for spurious interrupt
detection. An irq that uses this also won't get stats tracked since it
didn't generate the interrupt, nor added to randomness since they are
not random.

Signed-off-by: Keith Busch <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: [email protected]
Cc: Jon Derrick <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

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genirq: Use a common macro to go through the actions list

The irq code browses the list of actions differently to inspect the element
one by one. Even if it is not a problem, for the sake of consist

genirq: Use a common macro to go through the actions list

The irq code browses the list of actions differently to inspect the element
one by one. Even if it is not a problem, for the sake of consistent code,
provide a macro similar to for_each_irq_desc in order to have the same loop to
go through the actions list and use it in the code.

[ tglx: Renamed the macro ]

Signed-off-by: Daniel Lezcano <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

show more ...

genirq: Validate action before dereferencing it in handle_irq_event_percpu()

commit 71f64340fc0e changed the handling of irq_desc->action from

CPU 0 CPU 1
free_irq()

genirq: Validate action before dereferencing it in handle_irq_event_percpu()

commit 71f64340fc0e changed the handling of irq_desc->action from

CPU 0 CPU 1
free_irq() lock(desc)
lock(desc) handle_edge_irq()
if (desc->action) {
handle_irq_event()
action = desc->action
unlock(desc)
desc->action = NULL handle_irq_event_percpu(desc, action)
action->xxx
to

CPU 0 CPU 1
free_irq() lock(desc)
lock(desc) handle_edge_irq()
if (desc->action) {
handle_irq_event()
unlock(desc)
desc->action = NULL handle_irq_event_percpu(desc, action)
action = desc->action
action->xxx

So if free_irq manages to set the action to NULL between the unlock and before
the readout, we happily dereference a null pointer.

We could simply revert 71f64340fc0e, but we want to preserve the better code
generation. A simple solution is to change the action loop from a do {} while
to a while {} loop.

This is safe because we either see a valid desc->action or NULL. If the action
is about to be removed it is still valid as free_irq() is blocked on
synchronize_irq().

CPU 0 CPU 1
free_irq() lock(desc)
lock(desc) handle_edge_irq()
handle_irq_event(desc)
set(INPROGRESS)
unlock(desc)
handle_irq_event_percpu(desc)
action = desc->action
desc->action = NULL while (action) {
action->xxx
...
action = action->next;
sychronize_irq()
while(INPROGRESS); lock(desc)
clr(INPROGRESS)
free(action)

That's basically the same mechanism as we have for shared
interrupts. action->next can become NULL while handle_irq_event_percpu()
runs. Either it sees the action or NULL. It does not matter, because action
itself cannot go away before the interrupt in progress flag has been cleared.

Fixes: commit 71f64340fc0e "genirq: Remove the second parameter from handle_irq_event_percpu()"
Reported-by: [email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Huang Shijie <[email protected]>
Cc: Jiang Liu <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1601131224190.3575@nanos

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genirq: Fix handle_bad_irq kerneldoc comment

A recent cleanup removed the 'irq' parameter from many functions, but
left the documentation for this in place for at least one function.

This removes i

genirq: Fix handle_bad_irq kerneldoc comment

A recent cleanup removed the 'irq' parameter from many functions, but
left the documentation for this in place for at least one function.

This removes it.

Fixes: bd0b9ac405e1 ("genirq: Remove irq argument from irq flow handlers")
Reported-by: kbuild test robot <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Cc: Grygorii Strashko <[email protected]>
Cc: Tony Lindgren <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: [email protected]
Cc: Austin Schuh <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/5400000.cD19rmgWjV@wuerfel
Signed-off-by: Thomas Gleixner <[email protected]>

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genirq: Export handle_bad_irq

A cleanup of the omap gpio driver introduced a use of the
handle_bad_irq() function in a device driver that can be
a loadable module.

This broke the ARM allmodconfig b

genirq: Export handle_bad_irq

A cleanup of the omap gpio driver introduced a use of the
handle_bad_irq() function in a device driver that can be
a loadable module.

This broke the ARM allmodconfig build:

ERROR: "handle_bad_irq" [drivers/gpio/gpio-omap.ko] undefined!

This patch exports the handle_bad_irq symbol in order to
allow the use in modules.

Signed-off-by: Arnd Bergmann <[email protected]>
Cc: Grygorii Strashko <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: Austin Schuh <[email protected]>
Cc: Tony Lindgren <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/5847725.4IBopItaOr@wuerfel
Signed-off-by: Thomas Gleixner <[email protected]>

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genirq: Remove the second parameter from handle_irq_event_percpu()

Actually, we always use the first irq action of the @desc->action
chain, so remove the second parameter from handle_irq_event_percp

genirq: Remove the second parameter from handle_irq_event_percpu()

Actually, we always use the first irq action of the @desc->action
chain, so remove the second parameter from handle_irq_event_percpu()
which makes the code more tidy.

Signed-off-by: Huang Shijie <[email protected]>
Reviewed-by: Jiang Liu <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

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genirq: Remove irq argument from irq flow handlers

Most interrupt flow handlers do not use the irq argument. Those few
which use it can retrieve the irq number from the irq descriptor.

Remove the a

genirq: Remove irq argument from irq flow handlers

Most interrupt flow handlers do not use the irq argument. Those few
which use it can retrieve the irq number from the irq descriptor.

Remove the argument.

Search and replace was done with coccinelle and some extra helper
scripts around it. Thanks to Julia for her help!

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Julia Lawall <[email protected]>
Cc: Jiang Liu <[email protected]>

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genirq: Remove the irq argument from note_interrupt()

Only required for the slow path. Retrieve it from irq descriptor if
necessary.

[ tglx: Split out from combo patch. Left [try_]misrouted_irq()

genirq: Remove the irq argument from note_interrupt()

Only required for the slow path. Retrieve it from irq descriptor if
necessary.

[ tglx: Split out from combo patch. Left [try_]misrouted_irq()
untouched as there is no win in the slow path ]

Signed-off-by: Jiang Liu <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Yinghai Lu <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Jason Cooper <[email protected]>
Cc: Kevin Cernekee <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

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genirq: Remove the parameter 'irq' of kstat_incr_irqs_this_cpu()

The first parameter 'irq' is never used by
kstat_incr_irqs_this_cpu(). Remove it.

Signed-off-by: Jiang Liu <[email protected]

genirq: Remove the parameter 'irq' of kstat_incr_irqs_this_cpu()

The first parameter 'irq' is never used by
kstat_incr_irqs_this_cpu(). Remove it.

Signed-off-by: Jiang Liu <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Yinghai Lu <[email protected]>
Cc: Borislav Petkov <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

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genirq: Export symbol no_action()

This will allow to use the dummy IRQ handler no_action() from drivers
compiled as module. Drivers which use ARM FIQ interrupts can use this
to request the interrupt

genirq: Export symbol no_action()

This will allow to use the dummy IRQ handler no_action() from drivers
compiled as module. Drivers which use ARM FIQ interrupts can use this
to request the interrupt via the normal request_irq() mechanism w/o
having to copy the dummy handler to their own code.

Signed-off-by: Alexander Shiyan <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

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genirq: Provide irq_wake_thread()

In course of the sdhci/sdio discussion with Russell about killing the
sdio kthread hackery we discovered the need to be able to wake an
interrupt thread from softwa

genirq: Provide irq_wake_thread()

In course of the sdhci/sdio discussion with Russell about killing the
sdio kthread hackery we discovered the need to be able to wake an
interrupt thread from software.

The rationale for this is, that sdio hardware can lack proper
interrupt support for certain features. So the driver needs to poll
the status registers, but at the same time it needs to be woken up by
an hardware interrupt.

To be able to get rid of the home brewn kthread construct of sdio we
need a way to wake an irq thread independent of an actual hardware
interrupt.

Provide an irq_wake_thread() function which wakes up the thread which
is associated to a given dev_id. This allows sdio to invoke the irq
thread from the hardware irq handler via the IRQ_WAKE_THREAD return
value and provides a possibility to wake it via a timer for the
polling scenarios. That allows to simplify the sdio logic
significantly.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Russell King <[email protected]>
Cc: Chris Ball <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]

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random: make 'add_interrupt_randomness()' do something sane

We've been moving away from add_interrupt_randomness() for various
reasons: it's too expensive to do on every interrupt, and flooding the

random: make 'add_interrupt_randomness()' do something sane

We've been moving away from add_interrupt_randomness() for various
reasons: it's too expensive to do on every interrupt, and flooding the
CPU with interrupts could theoretically cause bogus floods of entropy
from a somewhat externally controllable source.

This solves both problems by limiting the actual randomness addition
to just once a second or after 64 interrupts, whicever comes first.
During that time, the interrupt cycle data is buffered up in a per-cpu
pool. Also, we make sure the the nonblocking pool used by urandom is
initialized before we start feeding the normal input pool. This
assures that /dev/urandom is returning unpredictable data as soon as
possible.

(Based on an original patch by Linus, but significantly modified by
tytso.)

Tested-by: Eric Wustrow <[email protected]>
Reported-by: Eric Wustrow <[email protected]>
Reported-by: Nadia Heninger <[email protected]>
Reported-by: Zakir Durumeric <[email protected]>
Reported-by: J. Alex Halderman <[email protected]>.
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
Cc: [email protected]

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