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SubjectRe: 2.5.63: 'Debug: sleeping function called from illegal context
Alan wrote:

>On Sat, 2003-03-01 at 21:05, Dr. David Alan Gilbert wrote:
>> Hi,
>> 2.5.63 had a good go at trying to boot for me; the only error during
>> boot was 'Debug: sleeping function called from illegal context at
>> mm/slab.c:1617' during the IDE startup.
>
>Known problem. Its a bug in the request_irq code on x86. IDE just
>happens to be a victim of it.
>
>
I would call it an IDE bug: request_irq is not atomic, there are dozends
of kmalloc(GFP_KERNEL) calls in the implementation.
And on some archs it might be impossible to implement it without
sleeping - e.g. on a NUMA arch an IPI to the right node could be necessary.
What about fixing ide? If ide can't handle early interrupts, then it can use

disable_irq();
request_irq();
spin_lock_irq(&ide_lock);
do_setup();
spin_unlock_irq(&ide_lock);
enable_irq();

I've attached a proposal - what do you think?
--
Manfred
// $Header$
// Kernel Version:
// VERSION = 2
// PATCHLEVEL = 5
// SUBLEVEL = 63
// EXTRAVERSION =
--- 2.5/include/linux/ide.h 2003-02-26 19:08:43.000000000 +0100
+++ build-2.5/include/linux/ide.h 2003-03-02 10:51:19.000000000 +0100
@@ -1730,6 +1730,19 @@
extern int ide_set_xfer_rate(ide_drive_t *drive, u8 rate);

extern spinlock_t ide_lock;
+extern struct semaphore ide_cfg_sem;
+/*
+ * Structure locking:
+ *
+ * ide_cfg_sem and ide_lock together protect changes to
+ * ide_hwif_t->{next,hwgroup}
+ * ide_drive_t->next
+ *
+ * ide_hwgroup_t->busy: ide_lock
+ * ide_hwgroup_t->hwif: ide_lock
+ * ide_hwif_t->mate: constant, no locking
+ * ide_drive_t->hwif: constant, no locking
+ */

#define local_irq_set(flags) do { local_save_flags((flags)); local_irq_enable(); } while (0)

--- 2.5/drivers/ide/ide-probe.c 2003-02-26 19:08:29.000000000 +0100
+++ build-2.5/drivers/ide/ide-probe.c 2003-03-02 11:15:40.000000000 +0100
@@ -1032,16 +1032,17 @@
*/
static int init_irq (ide_hwif_t *hwif)
{
- unsigned long flags;
unsigned int index;
+ int do_enable_irq;
ide_hwgroup_t *hwgroup, *new_hwgroup;
ide_hwif_t *match = NULL;

/* Allocate the buffer and potentially sleep first */
new_hwgroup = kmalloc(sizeof(ide_hwgroup_t),GFP_KERNEL);
-
- spin_lock_irqsave(&ide_lock, flags);

+ BUG_ON(in_interrupt());
+ BUG_ON(irqs_disabled());
+ down(&ide_cfg_sem);
hwif->hwgroup = NULL;
#if MAX_HWIFS > 1
/*
@@ -1078,7 +1079,7 @@
} else {
hwgroup = new_hwgroup;
if (!hwgroup) {
- spin_unlock_irqrestore(&ide_lock, flags);
+ up(&ide_cfg_sem);
return 1;
}
memset(hwgroup, 0, sizeof(ide_hwgroup_t));
@@ -1095,6 +1096,7 @@
/*
* Allocate the irq, if not already obtained for another hwif
*/
+ do_enable_irq = 0;
if (!match || match->irq != hwif->irq) {
int sa = SA_INTERRUPT;
#if defined(__mc68000__) || defined(CONFIG_APUS)
@@ -1112,17 +1114,23 @@
/* clear nIEN */
hwif->OUTB(0x08, hwif->io_ports[IDE_CONTROL_OFFSET]);

+ disable_irq(hwif->irq);
if (request_irq(hwif->irq,&ide_intr,sa,hwif->name,hwgroup)) {
if (!match)
kfree(hwgroup);
- spin_unlock_irqrestore(&ide_lock, flags);
+ enable_irq(&hwif->irq);
+ up(&ide_cfg_sem);
return 1;
}
+ do_enable_irq = 1;
}

/*
* Everything is okay, so link us into the hwgroup
*/
+ spin_lock_irq(&ide_lock);
+ if(do_enable_irq)
+ enable_irq(hwif->irq);
hwif->hwgroup = hwgroup;
hwif->next = hwgroup->hwif->next;
hwgroup->hwif->next = hwif;
@@ -1135,9 +1143,9 @@
hwgroup->drive = drive;
drive->next = hwgroup->drive->next;
hwgroup->drive->next = drive;
- spin_unlock_irqrestore(&ide_lock, flags);
+ spin_unlock_irq(&ide_lock);
ide_init_queue(drive);
- spin_lock_irqsave(&ide_lock, flags);
+ spin_lock_irq(&ide_lock);
}

if (!hwgroup->hwif) {
@@ -1148,7 +1156,7 @@
}

/* all CPUs; safe now that hwif->hwgroup is set up */
- spin_unlock_irqrestore(&ide_lock, flags);
+ spin_unlock_irq(&ide_lock);

#if !defined(__mc68000__) && !defined(CONFIG_APUS) && !defined(__sparc__)
printk("%s at 0x%03lx-0x%03lx,0x%03lx on irq %d", hwif->name,
@@ -1168,6 +1176,7 @@
printk(" (%sed with %s)",
hwif->sharing_irq ? "shar" : "serializ", match->name);
printk("\n");
+ up(&ide_cfg_sem);
return 0;
}

--- 2.5/drivers/ide/ide.c 2003-02-26 19:08:29.000000000 +0100
+++ build-2.5/drivers/ide/ide.c 2003-03-02 11:04:16.000000000 +0100
@@ -177,6 +177,7 @@
static int system_bus_speed; /* holds what we think is VESA/PCI bus speed */
static int initializing; /* set while initializing built-in drivers */

+DECLARE_MUTEX(ide_cfg_sem);
spinlock_t ide_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;

static int ide_scan_direction; /* THIS was formerly 2.2.x pci=reverse */
@@ -584,13 +585,15 @@
ide_hwif_t *hwif, *g;
ide_hwgroup_t *hwgroup;
int irq_count = 0, unit, i;
- unsigned long flags;
ide_hwif_t old_hwif;

if (index >= MAX_HWIFS)
BUG();

- spin_lock_irqsave(&ide_lock, flags);
+ BUG_ON(in_interrupt());
+ BUG_ON(irqs_disabled());
+ down(&ide_cfg_sem);
+ spin_lock_irq(&ide_lock);
hwif = &ide_hwifs[index];
if (!hwif->present)
goto abort;
@@ -605,7 +608,7 @@
}
hwif->present = 0;

- spin_unlock_irqrestore(&ide_lock, flags);
+ spin_unlock_irq(&ide_lock);

for (unit = 0; unit < MAX_DRIVES; ++unit) {
drive = &hwif->drives[unit];
@@ -618,7 +621,6 @@
#ifdef CONFIG_PROC_FS
destroy_proc_ide_drives(hwif);
#endif
- spin_lock_irqsave(&ide_lock, flags);
hwgroup = hwif->hwgroup;

/*
@@ -633,6 +635,7 @@
if (irq_count == 1)
free_irq(hwif->irq, hwgroup);

+ spin_lock_irq(&ide_lock);
/*
* Note that we only release the standard ports,
* and do not even try to handle any extra ports
@@ -813,7 +816,8 @@

hwif->hwif_data = old_hwif.hwif_data;
abort:
- spin_unlock_irqrestore(&ide_lock, flags);
+ spin_unlock_irq(&ide_lock);
+ up(&ide_cfg_sem);
}

EXPORT_SYMBOL(ide_unregister);
--- 2.5/drivers/ide/ide-io.c 2003-01-03 22:37:31.000000000 +0100
+++ build-2.5/drivers/ide/ide-io.c 2003-03-02 10:32:48.000000000 +0100
@@ -745,8 +745,8 @@
/* for atari only: POSSIBLY BROKEN HERE(?) */
ide_get_lock(ide_intr, hwgroup);

- /* necessary paranoia: ensure IRQs are masked on local CPU */
- local_irq_disable();
+ /* caller must own ide_lock */
+ BUG_ON(!irqs_disabled());

while (!hwgroup->busy) {
hwgroup->busy = 1;
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