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Commit 005a5a06 authored by Jeff Garzik's avatar Jeff Garzik
Browse files

[libata] locking rewrite (== fix) 

A lot of power packed into a little patch.

This change eliminates the sharing between our controller-wide spinlock
and the SCSI core's Scsi_Host lock.  As the locking in libata was
already highly compartmentalized, always referencing our own lock, and
never scsi_host::host_lock.

As a side effect, this change eliminates a deadlock from calling
scsi_finish_command() while inside our spinlock.
parent e5338254

drivers/scsi/libata-core.c

+0 −2
Original line number Original line Diff line number Diff line
@@ -4089,8 +4089,6 @@ static void ata_host_init(struct ata_port *ap, struct Scsi_Host *host, 
	host->unique_id = ata_unique_id++;

	host->unique_id = ata_unique_id++;

	host->max_cmd_len = 12;

	host->max_cmd_len = 12;





	scsi_assign_lock(host, &host_set->lock);



	ap->flags = ATA_FLAG_PORT_DISABLED;

	ap->flags = ATA_FLAG_PORT_DISABLED;

	ap->id = host->unique_id;

	ap->id = host->unique_id;

	ap->host = host;

	ap->host = host;

drivers/scsi/libata-scsi.c

+8 −1
Original line number Original line Diff line number Diff line
@@ -39,6 +39,7 @@ 
#include <scsi/scsi.h>

#include <scsi/scsi.h>

#include "scsi.h"

#include "scsi.h"

#include <scsi/scsi_host.h>

#include <scsi/scsi_host.h>

#include <scsi/scsi_device.h>

#include <linux/libata.h>

#include <linux/libata.h>

#include <linux/hdreg.h>

#include <linux/hdreg.h>

#include <asm/uaccess.h>

#include <asm/uaccess.h>
@@ -2405,8 +2406,12 @@ int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *)) 
	struct ata_port *ap;

	struct ata_port *ap;

	struct ata_device *dev;

	struct ata_device *dev;

	struct scsi_device *scsidev = cmd->device;

	struct scsi_device *scsidev = cmd->device;

	struct Scsi_Host *shost = scsidev->host;





	ap = (struct ata_port *) &scsidev->host->hostdata[0];

	ap = (struct ata_port *) &shost->hostdata[0];



	spin_unlock(shost->host_lock);

	spin_lock(&ap->host_set->lock);





	ata_scsi_dump_cdb(ap, cmd);

	ata_scsi_dump_cdb(ap, cmd);
@@ -2429,6 +2434,8 @@ int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *)) 
		ata_scsi_translate(ap, dev, cmd, done, atapi_xlat);

		ata_scsi_translate(ap, dev, cmd, done, atapi_xlat);





out_unlock:

out_unlock:

	spin_unlock(&ap->host_set->lock);

	spin_lock(shost->host_lock);

	return 0;

	return 0;

}

}