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    DateSat, 24 Sep 2005 09:07:04 +0200
    FromJens Axboe <>
    SubjectRe: [PATCH] updated version of Jens' SATA suspend-to-ram patch
    On Fri, Sep 23 2005, Jeff Garzik wrote:
    > >--- linux-2.6.13/drivers/scsi/libata-core.c~	2005-09-01 
    > >12:22:19.000000000 +0200
    > >+++ linux-2.6.13/drivers/scsi/libata-core.c	2005-09-01 
    > >12:24:38.000000000 +0200
    > >@@ -3738,8 +3738,8 @@
    > > 	unsigned long flags;
    > > 	int rc;
    > > 
    > >-	qc = ata_qc_new_init(ap, dev);
    > >-	BUG_ON(qc == NULL);
    > >+	while ((qc = ata_qc_new_init(ap, dev)) == NULL)
    > >+		msleep(10);
    > > 
    > > 	qc->tf.command = cmd;
    > > 	qc->tf.flags |= ATA_TFLAG_DEVICE;
    > 
    > Worried now!
    > 
    > If this patch is needed, something VERY VERY WRONG is going on.  This 
    > patch indicates that the queueing state machine has been violated, and 
    > something is trying to IGNORE the command synchronization :(
    
    I haven't diagnosed this further and it only ever happened in the SUSE
    kernel to my knowledge (no one has reported it to me for the vanilla
    kernels + suspend patch).
    
    So lets just keep this patch out of the equation for now, it could be
    that other SUSE patches broke something in this area :/
    
    > Further, you cannot always assume that msleep() is valid in that 
    > context.  It should be the caller that waits (libata suspend code), not 
    > ata_do_simple_cmd() itself.
    
    ata_do_simple_cmd() always blocks anyways, so I don't see the point.
    Perhaps rename the function to ata_execute_and_wait_simple_cmd().
    
    -- 
    Jens Axboe
    
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