Re: PATCH: 2.6.10 - Misrouted IRQ recovery for review

From: Dmitry Torokhov
Date: Tue Dec 28 2004 - 13:52:18 EST

On Tuesday 28 December 2004 01:25 pm, David S. Miller wrote:
> On Tue, 28 Dec 2004 12:28:27 -0500
> Dmitry Torokhov <dtor_core@xxxxxxxxxxxxx> wrote:
>
> > From what I saw the only thing that presently uses pt_rergs is SysRq
> > handler to print the call trace and if we slightly change the semantics
> > (instead of printing the trace immediately raise a flag and when next
> > interrupt arrives check it in do_IRQ and print the trace from there -
> > I even had some patches) we could drop pt_regs. I would very much like
> > to do so at least for input drivers.
>
> Are you going to take a snapshot at IRQ time? If not, then I'm
> pretty much against this change. When I do a sysrq regs dump,
> I want the exact pt_regs values at interrupt time, not some
> random value later in time.
>
> Perhaps instead you could raise a flag in the input driver, and
> at the top-level interrupt dispatch arch code do the register
> sysrq dump. This gives the same semantics as present, and also
> allows you what you want for the input drivers.
>

Please look at the patch below (handful of arches only and against
some old tree, but you'll see what I wanted to do). What I meant
by changing the semantics is that reporting is delayed by 1 interrupt.

> But, even with this, there is the x86 interrupt handler Alan
> mentioned which wants the pt_regs too.

This is for only one IRQ handler I believe which I think we can
do special-case for. Is it for math-emulation only?

--
Dmitry

===== arch/alpha/kernel/irq.c 1.29 vs edited =====
--- 1.29/arch/alpha/kernel/irq.c Thu Apr 22 03:40:34 2004
+++ edited/arch/alpha/kernel/irq.c Wed May 12 23:59:19 2004
@@ -25,6 +25,7 @@
#include <linux/irq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
+#include <linux/sysrq.h>

#include <asm/system.h>
#include <asm/io.h>
@@ -679,6 +680,8 @@
spin_unlock(&desc->lock);

irq_exit();
+
+ sysrq_irq_show_registers(regs);
}

/*
===== arch/i386/kernel/irq.c 1.52 vs edited =====
--- 1.52/arch/i386/kernel/irq.c Mon Apr 12 12:54:45 2004
+++ edited/arch/i386/kernel/irq.c Wed May 12 23:30:51 2004
@@ -34,6 +34,7 @@
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>
+#include <linux/sysrq.h>

#include <asm/atomic.h>
#include <asm/io.h>
@@ -569,6 +570,8 @@
spin_unlock(&desc->lock);

irq_exit();
+
+ sysrq_irq_show_registers(&regs);

return 1;
}
===== arch/ia64/kernel/irq.c 1.37 vs edited =====
--- 1.37/arch/ia64/kernel/irq.c Fri Feb 27 20:13:48 2004
+++ edited/arch/ia64/kernel/irq.c Wed May 12 23:58:07 2004
@@ -35,6 +35,7 @@
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>
+#include <linux/sysrq.h>

#include <asm/atomic.h>
#include <asm/io.h>
@@ -524,6 +525,9 @@
desc->handler->end(irq);
spin_unlock(&desc->lock);
}
+
+ sysrq_irq_show_registers(regs);
+
return 1;
}

===== arch/ppc/kernel/irq.c 1.36 vs edited =====
--- 1.36/arch/ppc/kernel/irq.c Wed Feb 18 22:42:58 2004
+++ edited/arch/ppc/kernel/irq.c Thu May 13 00:04:55 2004
@@ -46,6 +46,7 @@
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/cpumask.h>
+#include <linux/sysrq.h>

#include <asm/uaccess.h>
#include <asm/bitops.h>
@@ -531,6 +532,7 @@
/* That's not SMP safe ... but who cares ? */
ppc_spurious_interrupts++;
irq_exit();
+ sysrq_irq_show_registers(regs);
}

unsigned long probe_irq_on (void)
===== arch/ppc64/kernel/irq.c 1.52 vs edited =====
--- 1.52/arch/ppc64/kernel/irq.c Mon Apr 12 12:54:06 2004
+++ edited/arch/ppc64/kernel/irq.c Thu May 13 00:06:17 2004
@@ -41,6 +41,7 @@
#include <linux/proc_fs.h>
#include <linux/random.h>
#include <linux/kallsyms.h>
+#include <linux/sysrq.h>

#include <asm/uaccess.h>
#include <asm/bitops.h>
@@ -617,6 +618,8 @@
timer_interrupt(regs);
}

+ sysrq_irq_show_registers(regs);
+
return 1; /* lets ret_from_int know we can do checks */
}

@@ -645,6 +648,8 @@
ppc_spurious_interrupts++;

irq_exit();
+
+ sysrq_irq_show_registers(regs);

return 1; /* lets ret_from_int know we can do checks */
}
===== arch/sparc/kernel/irq.c 1.28 vs edited =====
--- 1.28/arch/sparc/kernel/irq.c Sun Feb 22 17:34:53 2004
+++ edited/arch/sparc/kernel/irq.c Thu May 13 00:07:40 2004
@@ -30,6 +30,7 @@
#include <linux/threads.h>
#include <linux/spinlock.h>
#include <linux/seq_file.h>
+#include <linux/sysrq.h>

#include <asm/ptrace.h>
#include <asm/processor.h>
@@ -341,6 +342,7 @@
} while (action);
enable_pil_irq(irq);
irq_exit();
+ sysrq_irq_show_registers(regs);
}

#ifdef CONFIG_BLK_DEV_FD
===== arch/sparc64/kernel/irq.c 1.40 vs edited =====
--- 1.40/arch/sparc64/kernel/irq.c Tue Feb 24 22:04:19 2004
+++ edited/arch/sparc64/kernel/irq.c Thu May 13 00:14:43 2004
@@ -21,6 +21,7 @@
#include <linux/delay.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
+#include <linux/sysrq.h>

#include <asm/ptrace.h>
#include <asm/processor.h>
@@ -822,6 +823,7 @@
bp->flags &= ~IBF_INPROGRESS;
}
irq_exit();
+ sysrq_irq_show_registers(regs);
}

#ifdef CONFIG_BLK_DEV_FD
===== arch/x86_64/kernel/irq.c 1.22 vs edited =====
--- 1.22/arch/x86_64/kernel/irq.c Wed Feb 18 22:42:58 2004
+++ edited/arch/x86_64/kernel/irq.c Thu May 13 00:02:07 2004
@@ -33,6 +33,7 @@
#include <linux/irq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
+#include <linux/sysrq.h>

#include <asm/atomic.h>
#include <asm/io.h>
@@ -405,6 +406,9 @@
spin_unlock(&desc->lock);

irq_exit();
+
+ sysrq_irq_show_registers(regs);
+
return 1;
}

===== drivers/char/sysrq.c 1.29 vs edited =====
--- 1.29/drivers/char/sysrq.c Mon Jan 19 18:38:11 2004
+++ edited/drivers/char/sysrq.c Wed May 12 23:39:52 2004
@@ -135,12 +135,33 @@


/* SHOW SYSRQ HANDLERS BLOCK */
+unsigned int sysrq_register_dump_requested;
+static spinlock_t show_registers_lock = SPIN_LOCK_UNLOCKED;
+
+void __sysrq_irq_show_registers(struct pt_regs *pt_regs)
+{
+ unsigned long flags;
+ int doit = 0;
+
+ spin_lock_irqsave(&show_registers_lock, flags);
+ if (sysrq_register_dump_requested) {
+ sysrq_register_dump_requested--;
+ doit = 1;
+ }
+ spin_unlock_irqrestore(&show_registers_lock, flags);
+
+ if (doit)
+ show_regs(pt_regs);
+}

static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
- if (pt_regs)
- show_regs(pt_regs);
+ unsigned long flags;
+
+ spin_lock_irqsave(&show_registers_lock, flags);
+ sysrq_register_dump_requested++;
+ spin_unlock_irqrestore(&show_registers_lock, flags);
}
static struct sysrq_key_op sysrq_showregs_op = {
.handler = sysrq_handle_showregs,
===== include/linux/sysrq.h 1.5 vs edited =====
--- 1.5/include/linux/sysrq.h Wed May 7 23:18:01 2003
+++ edited/include/linux/sysrq.h Thu May 13 00:15:32 2004
@@ -31,13 +31,26 @@

void handle_sysrq(int, struct pt_regs *, struct tty_struct *);

-/*
+/*
* Nonlocking version of handle sysrq, used by sysrq handlers that need to
* call sysrq handlers
*/

void __handle_sysrq_nolock(int, struct pt_regs *, struct tty_struct *);

+
+/*
+ * Check whether register dump has been requested and print it
+ */
+extern unsigned int sysrq_register_dump_requested;
+void __sysrq_irq_show_registers(struct pt_regs *);
+static inline void sysrq_irq_show_registers(struct pt_regs *pt_regs)
+{
+ if (unlikely(sysrq_register_dump_requested != 0))
+ __sysrq_irq_show_registers(pt_regs);
+}
+
+
/*
* Sysrq registration manipulation functions
*/
@@ -70,7 +83,7 @@
__sysrq_unlock_table();
return retval;
}
-
+
static inline int register_sysrq_key(int key, struct sysrq_key_op *op_p)
{
return __sysrq_swap_key_ops(key, op_p, NULL);
@@ -90,5 +103,9 @@

#define register_sysrq_key(ig,nore) __reterr()
#define unregister_sysrq_key(ig,nore) __reterr()
+
+static inline void sysrq_irq_show_registers(struct pt_regs *pt_regs)
+{
+}

#endif
-
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