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From: Greg KH on 1 Jul 2010 18:30
2.6.33-stable review patch. If anyone has any objections, please let me know.

------------------

From: Tejun Heo <tj(a)kernel.org>

commit e7ecd435692ca9bde9d124be30b3a26e672ea6c2 upstream.

There are ATAPI devices which raise AN when hit by commands issued by
open(). This leads to infinite loop of AN -> MEDIA_CHANGE uevent ->
udev open() to check media -> AN.

Both ACS and SerialATA standards don't define in which case ATAPI
devices are supposed to raise or not raise AN. They both list media
insertion event as a possible use case for ATAPI ANs but there is no
clear description of what constitutes such events. As such, it seems
a bit too naive to export ANs directly to userland as MEDIA_CHANGE
events without further verification (which should behave similarly to
windows as it apparently is the only thing that some hardware vendors
are testing against).

This patch adds libata.atapi_an module parameter and disables ATAPI AN
by default for now.

Signed-off-by: Tejun Heo <tj(a)kernel.org>
Cc: Kay Sievers <kay.sievers(a)vrfy.org>
Cc: Nick Bowler <nbowler(a)elliptictech.com>
Cc: David Zeuthen <david(a)fubar.dk>
Signed-off-by: Jeff Garzik <jgarzik(a)redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
drivers/ata/libata-core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -159,6 +159,10 @@ int libata_allow_tpm = 0;
module_param_named(allow_tpm, libata_allow_tpm, int, 0444);
MODULE_PARM_DESC(allow_tpm, "Permit the use of TPM commands (0=off [default], 1=on)");

+static int atapi_an;
+module_param(atapi_an, int, 0444);
+MODULE_PARM_DESC(atapi_an, "Enable ATAPI AN media presence notification (0=0ff [default], 1=on)");
+
MODULE_AUTHOR("Jeff Garzik");
MODULE_DESCRIPTION("Library module for ATA devices");
MODULE_LICENSE("GPL");
@@ -2570,7 +2574,8 @@ int ata_dev_configure(struct ata_device
* to enable ATAPI AN to discern between PHY status
* changed notifications and ATAPI ANs.
*/
- if ((ap->flags & ATA_FLAG_AN) && ata_id_has_atapi_AN(id) &&
+ if (atapi_an &&
+ (ap->flags & ATA_FLAG_AN) && ata_id_has_atapi_AN(id) &&
(!sata_pmp_attached(ap) ||
sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf) == 0)) {
unsigned int err_mask;


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