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libata: disable ATAPI AN by default 

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@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Nick Bowler <nbowler@elliptictech.com>
Cc: David Zeuthen <david@fubar.dk>
Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Tejun Heo 2010-05-19 15:38:58 +02:00 committed by Jeff Garzik
parent 9a7780c9ac
commit e7ecd43569
1 changed files with 6 additions and 1 deletions
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7
drivers/ata/libata-core.c
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@ -160,6 +160,10 @@ 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");
@ -2510,7 +2514,8 @@ int ata_dev_configure(struct ata_device *dev)
* 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;