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Old 06-05-2010, 08:49 PM
Marco d'Itri
Default libata: disable ATAPI AN by default

----- Forwarded message from Tejun Heo <tj@kernel.org> -----

From: Tejun Heo <tj@kernel.org>
To: Jeff Garzik <jeff@garzik.org>,
"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>
CC: Kay Sievers <kay.sievers@vrfy.org>,
Nick Bowler <nbowler@elliptictech.com>,
David Zeuthen <david@fubar.dk>, linux-hotplug@vger.kernel.org,
Subject: [PATCH #upstream-fixes] 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
drivers/ata/libata-core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 49cffb6..5abab5d 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -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");
@@ -2572,7 +2576,8 @@ 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;
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----- End forwarded message -----


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