linux-kernel - [Patch -mm 3/3] s390: cio: Delay uevents for subchannels.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:	Thu, 29 Mar 2007 11:12:18 +0200
From:	Cornelia Huck <cornelia.huck@...ibm.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-s390 <linux-s390@...r.kernel.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>
Subject: [Patch -mm 3/3] s390: cio: Delay uevents for subchannels.

From: Cornelia Huck <cornelia.huck@...ibm.com>

We often have the situation that we register a subchannel and start
device recognition, only to find out that the device is not usable
after all, which triggers an unregister of the subchannel. This often
happens on hundreds of subchannels on a LPAR, leading to a storm of
events which aren't of any use. Therefore, use uevent_suppress to
delay the KOBJ_ADD uevent for a subchannel until we know that its
ccw_device is to be registered.

Signed-off-by: Cornelia Huck <cornelia.huck@...ibm.com>

---
 drivers/s390/cio/css.c    |    9 +++++++++
 drivers/s390/cio/device.c |    6 ++++++
 2 files changed, 15 insertions(+)

--- linux-2.6.21-rc5-mm1.orig/drivers/s390/cio/device.c
+++ linux-2.6.21-rc5-mm1/drivers/s390/cio/device.c
@@ -903,6 +903,12 @@ io_subchannel_register(struct work_struc
 		}
 		goto out;
 	}
+	/*
+	 * Now we know this subchannel will stay, we can throw
+	 * our delayed uevent.
+	 */
+	sch->dev.uevent_suppress = 0;
+	kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
 	/* make it known to the system */
 	ret = ccw_device_register(cdev);
 	if (ret) {
--- linux-2.6.21-rc5-mm1.orig/drivers/s390/cio/css.c
+++ linux-2.6.21-rc5-mm1/drivers/s390/cio/css.c
@@ -135,6 +135,15 @@ css_register_subchannel(struct subchanne
 	sch->dev.bus = &css_bus_type;
 	sch->dev.release = &css_subchannel_release;
 	sch->dev.groups = subch_attr_groups;
+	/*
+	 * We don't want to generate uevents for I/O subchannels that don't
+	 * have a working ccw device behind them since they will be
+	 * unregistered before they can be used anyway, so we delay the add
+	 * uevent until after device recognition was successful.
+	 */
+	if (!cio_is_console(sch->schid))
+		/* Console is special, no need to suppress. */
+		sch->dev.uevent_suppress = 1;
 
 	css_get_ssd_info(sch);
 
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/