[PATCH] touch softlockup watchdog in ide_wait_not_busy

From: Jesper Juhl (jesper.juhl_at_gmail.com)
Date: 11/29/05

  • Next message: Bartlomiej Zolnierkiewicz: "Re: ide-cd doesn't replace ide-scsi?" 
    To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Date:	Tue, 29 Nov 2005 15:55:26 +0100

    Hi,

    This is a resend of a patch I proposed in the
    "[BUG] 2.6.15-rc1, soft lockup detected while probing IDE devices on AMD7441"
    thread.
    I recieved no ACK/NACK or other feedback on the patch, so I'm resending it in
    the hope of getting some comments :)

    From: Jesper Juhl <jesper.juhl@gmail.com>

    Make sure we touch the softlockup watchdog in
    ide_wait_not_busy() since it may cause the watchdog to trigger, but
    there's really no point in that since the loop will eventually return, and
    triggering the watchdog won't do us any good anyway.

    The if (!(timeout % 128)) bit is a guess that since
    touch_softlockup_watchdog() is a per_cpu thing it will be cheaper to do the
    modulo calculation than calling the function every time through the loop,
    especially as the nr of CPU's go up. But it's purely a guess, so I may very
    well be wrong - also, 128 is an arbitrarily chosen value, it's just a nice
    number that'll give us <10 function calls pr second.

    Since I have no IDE devices in my box I'm unable to test this beyond making
    sure it compiles without warnings or errors (which it does).

    Let me know what you think.

    Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> 

    ---
 drivers/ide/ide-iops.c |    8 ++++++++
 1 files changed, 8 insertions(+)
diff -up linux-2.6.15-rc3-orig/drivers/ide/ide-iops.c linux-2.6.15-rc3/drivers/ide/ide-iops.c
--- linux-2.6.15-rc3-orig/drivers/ide/ide-iops.c	2005-11-29 15:30:32.000000000 +0100
+++ linux-2.6.15-rc3/drivers/ide/ide-iops.c	2005-11-29 15:44:23.000000000 +0100
@@ -24,6 +24,7 @@
 #include <linux/hdreg.h>
 #include <linux/ide.h>
 #include <linux/bitops.h>
+#include <linux/sched.h>
 
 #include <asm/byteorder.h>
 #include <asm/irq.h>
@@ -1243,6 +1244,13 @@ int ide_wait_not_busy(ide_hwif_t *hwif, 
 		 */
 		if (stat == 0xff)
 			return -ENODEV;
+
+		/* 
+		 * We risk triggering the soft lockup detector, but we don't
+		 * want that, so better poke it a bit once in a while.
+		 */
+		if (!(timeout % 128))
+			touch_softlockup_watchdog();
 	}
 	return -EBUSY;
 }
-
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