Commit Graph

52 Commits

Author SHA1 Message Date
Peter Zijlstra b54cb2332e parisc: remove IRQF_DISABLED
People are playing odd games with IRQF_DISABLED, remove it.

Its not reliable, since shared interrupt lines could disable it for you,
and its possible and allowed for archs to disable IRQs to limit IRQ nesting.

Therefore, simply mandate that _ALL_ IRQ handlers are run with IRQs disabled.

[ This _should_ not break anything, since we've mandated that IRQ handlers
  _must_ be able to deal with this for a _long_ time ]

IRQ handlers should be fast, no if buts and any other exceptions. We also have
plenty instrumentation to find any offending IRQ latency sources.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Helge Deller <deller@gmx.de>
2013-02-20 22:50:26 +01:00
John David Anglin cac1f12b9f parisc: don't claim cpu irqs more than once
The CPU irqs (timer and IPI) are not shared and only need to be claimed once.
A mismatch error occurs if they are claimed more than once.

Signed-off-by: John David Anglin <dave.anglin@nrc-cnrc.gc.ca>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Signed-off-by: Helge Deller <deller@gmx.de>
2013-01-07 23:06:23 +01:00
Thomas Gleixner 68f20f43da parisc: Use irq_to_desc() in show_interrupts()
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-03-29 14:48:08 +02:00
Thomas Gleixner e2f571d294 parisc: Convert irq namespace
Convert to the new function names. Scripted with coccinelle.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: linux-parisc@vger.kernel.org
2011-03-29 14:48:08 +02:00
Thomas Gleixner 337ce6811b parisc: Convert the final irq bits
1) As promised in the comment, the core does not copy cpumask anymore
   when the arch code returns -EINVAL

2) Get the per cpu information from irq_data

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: linux-parisc@vger.kernel.org
2011-03-29 14:48:08 +02:00
Thomas Gleixner 4c4231ea2f [PARISC] Convert to new irq_chip functions
Convert all the parisc driver interrupt handlers (dino, eisa, gsc,
iosapic and superio) as well as the cpu interrupts.  Prepare
show_interrupts for GENERIC_HARDIRQS_NO_DEPRECATED and finally selects
that Kconfig option

[jejb: compile and testing fixes]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
2011-02-10 10:22:14 -06:00
Thomas Gleixner 9804c9eaea [PARISC] fix per-cpu flag problem in the cpu affinity checkers
The CHECK_IRQ_PER_CPU is wrong, it should be checking
irq_to_desc(irq)->status not just irq.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
2011-02-09 13:06:07 -06:00
James Bottomley 51890613f2 parisc: convert the rest of the irq handlers to simple/percpu
The generic conversion eliminates the spurious no_ack and no_end
routines, converts all the cascaded handlers to handle_simple_irq() and
makes iosapic use a modified handle_percpu_irq() to become the same as
the CPU irq's.  This isn't an essential change, but it eliminates the
mask/unmask overhead of handle_level_irq().

Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2010-12-04 11:15:19 -05:00
James Bottomley d16cd297d2 parisc: fix dino/gsc interrupts
The essential problem we're currently having is that dino (and gsc) is a
cascaded CPU interrupt.  Under the old __do_IRQ() handler, our CPU
interrupts basically did an ack followed by an end.  In the new scheme,
we replaced them with level handlers which do a mask, an ack and then an
unmask (but no end).  Instead, with the renaming of end to eoi, we
actually want to call the percpu flow handlers, because they actually
have all the characteristics we want.

This patch does the conversion and gets my C360 booting again.

Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2010-12-04 11:14:32 -05:00
Kyle McMartin 7da1272547 parisc: kill __do_IRQ
Signed-off-by: Kyle McMartin <kyle@redhat.com>
2010-10-14 01:30:54 -04:00
Kyle McMartin f3d4605977 parisc: convert iosapic interrupts to proper flow handlers
Shift the ->end call (cpu eoi) from __do_IRQ into our
unmask handler. Also nuke some redundant code.

Signed-off-by: Kyle McMartin <kyle@redhat.com>
2010-10-14 01:30:16 -04:00
Kyle McMartin 4d4f681dc4 parisc: convert cpu interrupts to proper flow handlers
Only major change is renaming functions to match the conventions
expected by the generic irq code.

Signed-off-by: Kyle McMartin <kyle@redhat.com>
2010-10-14 01:30:13 -04:00
Kyle McMartin ba20085c20 parisc: lay groundwork for killing __do_IRQ
Use proper accessors and handlers for generic irq cleanups. We just
call back into __do_IRQ through desc->handler now, and remove the
explicit calls.

Signed-off-by: Kyle McMartin <kyle@redhat.com>
2010-10-14 01:30:11 -04:00
Thomas Gleixner d0608b5474 parisc: Fixup last users of irq_chip->typename
The typename member of struct irq_chip was kept for migration purposes
and is obsolete since more than 2 years. Fix up the leftovers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2009-12-16 03:48:56 +00:00
Thomas Gleixner 239007b844 genirq: Convert irq_desc.lock to raw_spinlock
Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
2009-12-14 23:55:33 +01:00
Christoph Hellwig 9609bfec6d parisc: convert to asm-generic/hardirq.h
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2009-09-28 00:24:23 -04:00
Thomas Gleixner dfe0756502 parisc: remove obsolete hw_interrupt_type
The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t) have
been kept around for migration reasons.  After more than two years it's
time to remove them finally.

This patch cleans up one of the remaining users.  When all such patches
hit mainline we can remove the defines and typedefs finally.

Impact: cleanup

Convert the last remaining users to struct irq_chip and remove the
define.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2009-07-03 03:34:08 +00:00
Helge Deller 47b4150baa parisc: fix irq compile bugs in arch/parisc/kernel/irq.c
Fix miscompilation in arch/parisc/kernel/irq.c:
123: warning: passing arg 1 of `cpumask_setall' from incompatible pointer type
141: warning: passing arg 1 of `cpumask_copy' from incompatible pointer type
300: warning: passing arg 1 of `cpumask_copy' from incompatible pointer type
357: warning: passing arg 2 of `cpumask_copy' from incompatible pointer type

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2009-07-03 03:34:07 +00:00
Yinghai Lu d5dedd4507 irq: change ->set_affinity() to return status
according to Ingo, change set_affinity() in irq_chip should return int,
because that way we can handle failure cases in a much cleaner way, in
the genirq layer.

v2: fix two typos

[ Impact: extend API ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-arch@vger.kernel.org
LKML-Reference: <49F654E9.4070809@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-28 12:21:16 +02:00
Kyle McMartin 7cec2ef4a2 Merge branch 'rusty-cpumask-parisc' into parisc 2009-04-02 01:43:14 +00:00
Ingo Molnar 6e15cf0486 Merge branch 'core/percpu' into percpu-cpumask-x86-for-linus-2
Conflicts:
	arch/parisc/kernel/irq.c
	arch/x86/include/asm/fixmap_64.h
	arch/x86/include/asm/setup.h
	kernel/irq/handle.c

Semantic merge:
        arch/x86/include/asm/fixmap.h

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-27 17:28:43 +01:00
Ingo Molnar edb35028e4 Merge branches 'irq/genirq' and 'linus' into irq/core 2009-03-16 09:20:13 +01:00
Rusty Russell bd071e1a37 cpumask: prepare for iterators to only go to nr_cpu_ids/nr_cpumask_bits.: parisc
Impact: cleanup, futureproof

In fact, all cpumask ops will only be valid (in general) for bit
numbers < nr_cpu_ids.  So use that instead of NR_CPUS in various
places.

This is always safe: no cpu number can be >= nr_cpu_ids, and
nr_cpu_ids is initialized to NR_CPUS at boot.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
2009-03-16 14:19:37 +10:30
Kyle McMartin 8b6649c575 parisc: convert cpu_check_affinity to new cpumask api
cpumask arg to the affinity function is now const, sort
that out through the irq_desc implementations.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2009-03-13 01:20:27 -04:00
Kyle McMartin 7c4be70e6d parisc: fix use of new cpumask api in irq.c
cpumask api needs to take a pointer to irq_desc[cpu].affinity

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2009-03-13 01:20:01 -04:00
Mike Travis 5a8247ca4c parisc: update parisc for new irq_desc
Impact: cleanup, update to new cpumask API

Irq_desc.affinity and irq_desc.pending_mask are now cpumask_var_t's
so access to them should be using the new cpumask API.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2009-03-13 01:19:49 -04:00
Mike Travis e65e49d0f3 irq: update all arches for new irq_desc
Impact: cleanup, update to new cpumask API

Irq_desc.affinity and irq_desc.pending_mask are now cpumask_var_t's
so access to them should be using the new cpumask API.

Signed-off-by: Mike Travis <travis@sgi.com>
2009-01-12 15:27:13 -08:00
Yinghai Lu dee4102a9a sparseirq: use kstat_irqs_cpu instead
Impact: build fix

Ingo Molnar wrote:

> tip/arch/blackfin/kernel/irqchip.c: In function 'show_interrupts':
> tip/arch/blackfin/kernel/irqchip.c:85: error: 'struct kernel_stat' has no member named 'irqs'
> make[2]: *** [arch/blackfin/kernel/irqchip.o] Error 1
> make[2]: *** Waiting for unfinished jobs....
>

So could move kstat_irqs array to irq_desc struct.

(s390, m68k, sparc) are not touched yet, because they don't support genirq

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-11 15:53:13 +01:00
Helge Deller ef017bebd0 parisc: Replace NR_CPUS in parisc code
parisc: Replace most arrays sized by NR_CPUS with percpu variables.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2009-01-05 19:09:02 +00:00
Helge Deller 7f2347a44d parisc: trivial fixes
trivial fixes:
- use KERN_WARNING for printk()
- use BUG_ON() instead of "if (xx) BUG();"

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

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2009-01-05 19:00:21 +00:00
Rusty Russell 0de26520c7 cpumask: make irq_set_affinity() take a const struct cpumask
Impact: change existing irq_chip API

Not much point with gentle transition here: the struct irq_chip's
setaffinity method signature needs to change.

Fortunately, not widely used code, but hits a few architectures.

Note: In irq_select_affinity() I save a temporary in by mangling
irq_desc[irq].affinity directly.  Ingo, does this break anything?

(Folded in fix from KOSAKI Motohiro)

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Grant Grundler <grundler@parisc-linux.org>
Acked-by: Ingo Molnar <mingo@redhat.com>
Cc: ralf@linux-mips.org
Cc: grundler@parisc-linux.org
Cc: jeremy@xensource.com
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
2008-12-13 21:20:26 +10:30
Kyle McMartin 2421ba5b57 [PARISC] timer interrupt should not be IRQ_DISABLED
The timer interrupt had accidentally been marked IRQ_DISABLED since
IRQ_PER_CPU had been OR-ed in, instead of set. This had been working
by accident for quite a while.

Commit c642b8391c changed the behaviour of
IRQ_PER_CPU interrupts, which previously weren't checked for IRQ_DISABLED.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2007-12-06 09:16:45 -08:00
Grant Grundler 462b529f91 [PARISC] remove global_ack_eiem
Kudos to Thibaut Varene for spotting the (mis)use of appropriately named
global_ack_eiem. This took a long time to figure out and both insight
from myself, Kyle McMartin, and James Bottomley were required to narrow
down which bit of code could have this race condition.

The symptom was interrupts stopped getting delivered while some workload
was generating IO interrupts on two different CPUs. One of the interrupt
sources would get masked off and stay unmasked. Problem was global_ack_eiem
was accessed with read/modified/write sequence and not protected by
a spinlock.

PA-RISC doesn't need a global ack flag though. External Interrupts
are _always_ delivered to a single CPU (except for "global broadcast
interrupt" which AFAIK currently is not used.) So we don't have to worry
about any given IRQ vector getting delivered to more than one CPU.

Tested on a500 and rp34xx boxen. rsync to/from gsyprf11 (a500)
would lock up the box since NIC (tg3) interrupt and SCSI (sym2)
were on "opposite" CPUs (2 CPU system). Put them on the same CPU
or apply this patch and 10GB of data would rsync completely.

Please apply the following critical patch.

thanks,
grant

Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Acked-by: Thibaut VARENE <T-Bone@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2007-06-12 01:23:30 -04:00
Bernhard Walle 57501c7074 Add IRQF_IRQPOLL flag on parisc
Add IRQF_IRQPOLL to the timer interrupt on parisc.

Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <willy@debian.org>
Cc: Grant Grundler <grundler@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:22 -07:00
Kyle McMartin 0c2de3c6c4 [PARISC] use fls_long in irq.c
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2007-02-17 01:00:25 -05:00
Matthew Wilcox e11e30a063 [PARISC] Use set_irq_regs
Actually set the irq_regs pointer.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
2006-10-07 05:11:07 -06:00
Matthew Wilcox be577a5220 Build fixes for struct pt_regs removal
Signed-off-by: Matthew Wilcox <matthew@wil.cx>
2006-10-06 20:47:23 -06:00
James Bottomley 7085689ed1 [PARISC] Allow nested interrupts
Our prior mode of operation didn't allow nested interrupts
because it makes the interrupt code much simpler.  However,
nested interrupts are better for latency.

This code uses the EIEM register to simulate level interrupts
and thus achieve nesting.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-10-04 06:48:57 -06:00
Kyle McMartin 5cfe87d3f5 [PARISC] Fix up parisc irq handling for genirq changes
Clean up enough to get things compiling again in the interim.

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2006-10-04 06:45:59 -06:00
Thomas Gleixner 733ea869e5 [PATCH] irq-flags: PARISC: Use the new IRQF_ constants
Use the new IRQF_ constants and remove the SA_INTERRUPT define

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-02 13:58:47 -07:00
Jörn Engel 6ab3d5624e Remove obsolete #include <linux/config.h>
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-06-30 19:25:36 +02:00
Ingo Molnar c0ad90a32f [PATCH] genirq: add ->retrigger() irq op to consolidate hw_irq_resend()
Add ->retrigger() irq op to consolidate hw_irq_resend() implementations.
(Most architectures had it defined to NOP anyway.)

NOTE: ia64 needs testing. i386 and x86_64 tested.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-29 10:26:23 -07:00
Ingo Molnar a53da52fd7 [PATCH] genirq: cleanup: merge irq_affinity[] into irq_desc[]
Consolidation: remove the irq_affinity[NR_IRQS] array and move it into the
irq_desc[NR_IRQS].affinity field.

[akpm@osdl.org: sparc64 build fix]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-29 10:26:22 -07:00
Ingo Molnar d1bef4ed5f [PATCH] genirq: rename desc->handler to desc->chip
This patch-queue improves the generic IRQ layer to be truly generic, by adding
various abstractions and features to it, without impacting existing
functionality.

While the queue can be best described as "fix and improve everything in the
generic IRQ layer that we could think of", and thus it consists of many
smaller features and lots of cleanups, the one feature that stands out most is
the new 'irq chip' abstraction.

The irq-chip abstraction is about describing and coding and IRQ controller
driver by mapping its raw hardware capabilities [and quirks, if needed] in a
straightforward way, without having to think about "IRQ flow"
(level/edge/etc.) type of details.

This stands in contrast with the current 'irq-type' model of genirq
architectures, which 'mixes' raw hardware capabilities with 'flow' details.
The patchset supports both types of irq controller designs at once, and
converts i386 and x86_64 to the new irq-chip design.

As a bonus side-effect of the irq-chip approach, chained interrupt controllers
(master/slave PIC constructs, etc.) are now supported by design as well.

The end result of this patchset intends to be simpler architecture-level code
and more consolidation between architectures.

We reused many bits of code and many concepts from Russell King's ARM IRQ
layer, the merging of which was one of the motivations for this patchset.

This patch:

rename desc->handler to desc->chip.

Originally i did not want to do this, because it's a big patch.  But having
both "desc->handler", "desc->handle_irq" and "action->handler" caused a
large degree of confusion and made the code appear alot less clean than it
truly is.

I have also attempted a dual approach as well by introducing a
desc->chip alias - but that just wasnt robust enough and broke
frequently.

So lets get over with this quickly.  The conversion was done automatically
via scripts and converts all the code in the kernel.

This renaming patch is the first one amongst the patches, so that the
remaining patches can stay flexible and can be merged and split up
without having some big monolithic patch act as a merge barrier.

[akpm@osdl.org: build fix]
[akpm@osdl.org: another build fix]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-29 10:26:21 -07:00
Ryan Bradetich 75be99a8c5 [PARISC] Make redirecting irq messages less noisy
Make the "redirecting irq" message to not display on the console by
setting the severity to KERN_DEBUG.  The console was basically unusable.

Signed-off-by: Ryan Bradetich <rbrad@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17 16:29:50 -05:00
Grant Grundler 03afe22f07 [PARISC] irq_affinityp[] only available for SMP builds
irq_affinityp[] only available for SMP builds, make code that uses
it conditional on CONFIG_SMP.

Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17 16:29:16 -05:00
James Bottomley c2ab64d098 [PARISC] Add IRQ affinities
This really only adds them for the machines I can check SMP on, which
is CPU interrupts and IOSAPIC (so not any of the GSC based machines).

With this patch, irqbalanced can be used to maintain irq balancing.
Unfortunately, irqbalanced is a bit x86 centric, so it doesn't do an
incredibly good job, but it does work.

Signed-off-by: James Bottomley <jejb@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17 16:28:37 -05:00
Kyle McMartin 1d4c452a85 [PARISC] Fix uniprocessor build by dummying smp_send_all_nop()
Since irq.c uses smp_send_all_nop, we must define it for UP builds
as well. Make it a static inline so it gets optimized away. This forces
irq.c to include <asm/smp.h> though.

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17 16:27:44 -05:00
James Bottomley d911aed8ad [PARISC] Fix our interrupts not to use smp_call_function
Fix our interrupts not to use smp_call_function

On K and D class smp, the generic code calls this under an irq
spinlock, which causes the WARN_ON() message in smp_call_function()
(and is also illegal because it could deadlock).

The fix is to use a new scheme based on the IPI_NOP.

Signed-off-by: James Bottomley <jejb@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17 16:27:02 -05:00
Grant Grundler 3f902886a8 [PARISC] Disable nesting of interrupts
Disable nesting of interrupts - still has holes

The offending sequence starts out like this:
1) take external interrupt
2) set_eiem() to only allow TIMER_IRQ; local interrupts still disabled
3) read the EIRR to get a "list" of pending interrupts
4) clear EIRR of pending interrupts we intend to handle
5) call __do_IRQ() to handle IRQ.
6) handle_IRQ_event() enables local interrupts (I-Bit)
7) take a timer interrupt
8) read EIRR to get a new list of pending interrupts
9) clear EIRR of pending interrupts we just read
10) handle pending interrupts found in (8)
11) set_eiem(cpu_eiem) and return
        [ TROUBLE! all enabled CPU IRQs are unmasked. }
12) handle remaining interrupts pending from (3)
        e.g. call __do_IRQ() -> handle_IRQ_event()..etc
        [ TROUBLE! call to handle_IRQ_event() can now enable *any* IRQ. }
13) set_eiem(cpu_eiem) and return

The problem is we now get into ugly race conditions with Timer and IPI
interrupts at this point.  I'm not exactly sure what happens when
things go wrong (perhaps nest calls to IPI or timer interrupt?).
But I'm certain it's not good.

This sequence will break sooner if (10) would accidentally leave
interrupts enabled.

I'm pretty sure the right answer is now to make cpu_eiem
a per CPU variable since all external interrupts on parisc
are per CPU. This means we will NOT need to send an IPI to
every CPU in the system when enabling or disabling an IRQ
since only one CPU needs to change it's EIEM.

Thanks to James Bottomley for (once again) pointing out the problem.

Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
2005-11-17 16:26:20 -05:00