Messages in this thread Patch in this message | | | Date | Sat, 28 Jan 2006 17:02:40 +0100 | From | Ingo Molnar <> | Subject | Re: [patch] warn on release_region() from irq context |
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* Ingo Molnar <mingo@elte.hu> wrote:
> the rationale for this patch is that the lock validator (which now > tracks rwlock dependencies too, see output below) noticed that > floppy.c does a release_region() from softirq context -> ouch. I'm > working on the floppy.c fix for that.
ugh. floppy.c is a mess. I did the patch below - but that's not enough, it does stupid things like request_region() and release_region() from the timer irq - so floppy.c file needs a serious redesign to fix these deadlocks :-(
Ingo
floppy.c does alot of irq-unsafe work within floppy_release_irq_and_dma(): free_irq(), release_region() ... so when executing in irq context, push the whole function into keventd.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
----
drivers/block/floppy.c | 27 +++++++++++++++++++++++++-- 1 files changed, 25 insertions(+), 2 deletions(-)
Index: linux/drivers/block/floppy.c =================================================================== --- linux.orig/drivers/block/floppy.c +++ linux/drivers/block/floppy.c @@ -561,6 +561,21 @@ static int floppy_grab_irq_and_dma(void) static void floppy_release_irq_and_dma(void); /* + * Interrupt, DMA and region freeing must not be done from IRQ + * context - e.g. irq-unregistration means /proc VFS work, region + * release takes an irq-unsafe lock, etc. So we push this work + * into keventd: + */ +static void fd_release_fn(void *data) +{ + mutex_lock(&open_lock); + floppy_release_irq_and_dma(); + mutex_unlock(&open_lock); +} + +static DECLARE_WORK(floppy_release_irq_and_dma_work, fd_release_fn, NULL); + +/* * The "reset" variable should be tested whenever an interrupt is scheduled, * after the commands have been sent. This is to ensure that the driver doesn't * get wedged when the interrupt doesn't come because of a failed command. @@ -824,7 +839,7 @@ static int set_dor(int fdc, char mask, c if (newdor & FLOPPY_MOTOR_MASK) floppy_grab_irq_and_dma(); if (olddor & FLOPPY_MOTOR_MASK) - floppy_release_irq_and_dma(); + schedule_work(&floppy_release_irq_and_dma_work); return olddor; } @@ -905,6 +920,8 @@ static int _lock_fdc(int drive, int inte set_current_state(TASK_RUNNING); remove_wait_queue(&fdc_wait, &wait); + + flush_scheduled_work(); } command_status = FD_COMMAND_NONE; @@ -938,7 +955,7 @@ static inline void unlock_fdc(void) if (elv_next_request(floppy_queue)) do_fd_request(floppy_queue); spin_unlock_irqrestore(&floppy_lock, flags); - floppy_release_irq_and_dma(); + schedule_work(&floppy_release_irq_and_dma_work); wake_up(&fdc_wait); } @@ -4628,6 +4645,12 @@ void cleanup_module(void) del_timer_sync(&fd_timer); blk_cleanup_queue(floppy_queue); + /* + * Wait for any asynchronous floppy_release_irq_and_dma() + * calls to finish first: + */ + flush_scheduled_work(); + if (usage_count) floppy_release_irq_and_dma(); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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