Re: [PATCH] ata: fix sleep-while-holding-spinlock in sata_nv

From: Robert Hancock
Date: Tue May 20 2008 - 22:19:50 EST

Arjan van de Ven wrote:
From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Subject: [PATCH] ata: fix sleep-while-holding-spinlock in sata_nv

blk_queue_bounce_limit() is a sleeping function, so reorganize
the code a little to not call it while holding a spinlock.

Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
drivers/ata/sata_nv.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
index 858f706..a7bc56d 100644
--- a/drivers/ata/sata_nv.c
+++ b/drivers/ata/sata_nv.c
@@ -671,6 +671,11 @@ static int nv_adma_slave_config(struct scsi_device *sdev)
port1 = ap->host->ports[1]->private_data;
sdev0 = ap->host->ports[0]->link.device[0].sdev;
sdev1 = ap->host->ports[1]->link.device[0].sdev;
+ blk_queue_segment_boundary(sdev->request_queue, segment_boundary);
+ blk_queue_max_hw_segments(sdev->request_queue, sg_tablesize);
+ spin_unlock_irqrestore(ap->lock, flags);
if ((port0->flags & NV_ADMA_ATAPI_SETUP_COMPLETE) ||
(port1->flags & NV_ADMA_ATAPI_SETUP_COMPLETE)) {
/** We have to set the DMA mask to 32-bit if either port is in
@@ -701,14 +706,11 @@ static int nv_adma_slave_config(struct scsi_device *sdev)
- blk_queue_segment_boundary(sdev->request_queue, segment_boundary);
- blk_queue_max_hw_segments(sdev->request_queue, sg_tablesize);
ata_port_printk(ap, KERN_INFO,
"DMA mask 0x%llX, segment boundary 0x%lX, hw segs %hu\n",
(unsigned long long)*ap->host->dev->dma_mask,
segment_boundary, sg_tablesize);
- spin_unlock_irqrestore(ap->lock, flags);
return rc;

I'm not certain this is safe to do it quite this way. It would be better to keep that spinlock held so that no operations could be in progress on either port while these operations are happening.

It would be better to fix the regression from 419c434c35614609fd0c79d335c134bf4b88b30b in block/blk_settings.c that resulted in the blk_queue_bounce_limit allocation wrongly allocating emergency ISA pages in the first place as a 32-bit DMA mask does not need them.
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