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From: Greg KH <gregkh@suse.de>
To: linux-kernel@vger.kernel.org, stable@kernel.org
Cc: Justin Forbes <jmforbes@linuxtx.org>,
	Zwane Mwaikambo <zwane@arm.linux.org.uk>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Randy Dunlap <rdunlap@xenotime.net>,
	Dave Jones <davej@redhat.com>,
	Chuck Wolber <chuckw@quantumlinux.com>,
	Chris Wedgwood <reviews@ml.cw.f00f.org>,
	Michael Krufky <mkrufky@linuxtv.org>,
	Chuck Ebbert <cebbert@redhat.com>,
	Domenico Andreoli <cavokz@gmail.com>, Willy Tarreau <w@1wt.eu>,
	Rodrigo Rubira Branco <rbranco@la.checkpoint.com>,
	Jake Edge <jake@lwn.net>, Eugene Teo <eteo@redhat.com>,
	torvalds@linux-foundation.org, akpm@linux-foundation.org,
	alan@lxorguk.ukuu.org.uk, linux1394-devel@lists.sourceforge.net,
	Jay Fenlason <fenlason@redhat.com>,
	Stefan Richter <stefanr@s5r6.in-berlin.de>
Subject: [patch 25/57] firewire: fw-sbp2: fix races
Date: Tue, 4 Nov 2008 15:31:53 -0800	[thread overview]
Message-ID: <20081104233153.GZ659@suse.de> (raw)
In-Reply-To: <20081104233028.GA659@suse.de>

[-- Attachment #1: firewire-fw-sbp2-fix-races.patch --]
[-- Type: text/plain, Size: 3328 bytes --]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Jay Fenlason <fenlason@redhat.com>

Same as commit cd1f70fdb4823c97328a1f151f328eb36fafd579 upstream

1: There is a small race between queue_delayed_work() and its
   corresponding kref_get().  Do the kref_get first, and _put it again
   if the queue_delayed_work() failed, so there is no chance of the
   kref going to zero while the work is scheduled.
2: An SBP2_LOGOUT_REQUEST could be sent out with a login_id full of
   garbage.  Initialize it to an invalid value so we can tell if we
   ever got a valid login_id.
3: The node ID and generation may have changed but the new values may
   not yet have been recorded in lu and tgt when the final logout is
   attempted.  Use the latest values from the device in
   sbp2_release_target().

Signed-off-by: Jay Fenlason <fenlason@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/firewire/fw-sbp2.c |   36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

--- a/drivers/firewire/fw-sbp2.c
+++ b/drivers/firewire/fw-sbp2.c
@@ -172,6 +172,9 @@ struct sbp2_target {
 	int blocked;	/* ditto */
 };
 
+/* Impossible login_id, to detect logout attempt before successful login */
+#define INVALID_LOGIN_ID 0x10000
+
 /*
  * Per section 7.4.8 of the SBP-2 spec, a mgt_ORB_timeout value can be
  * provided in the config rom. Most devices do provide a value, which
@@ -791,9 +794,20 @@ static void sbp2_release_target(struct k
 			scsi_remove_device(sdev);
 			scsi_device_put(sdev);
 		}
-		sbp2_send_management_orb(lu, tgt->node_id, lu->generation,
-				SBP2_LOGOUT_REQUEST, lu->login_id, NULL);
-
+		if (lu->login_id != INVALID_LOGIN_ID) {
+			int generation, node_id;
+			/*
+			 * tgt->node_id may be obsolete here if we failed
+			 * during initial login or after a bus reset where
+			 * the topology changed.
+			 */
+			generation = device->generation;
+			smp_rmb(); /* node_id vs. generation */
+			node_id    = device->node_id;
+			sbp2_send_management_orb(lu, node_id, generation,
+						 SBP2_LOGOUT_REQUEST,
+						 lu->login_id, NULL);
+		}
 		fw_core_remove_address_handler(&lu->address_handler);
 		list_del(&lu->link);
 		kfree(lu);
@@ -808,19 +822,20 @@ static void sbp2_release_target(struct k
 
 static struct workqueue_struct *sbp2_wq;
 
+static void sbp2_target_put(struct sbp2_target *tgt)
+{
+	kref_put(&tgt->kref, sbp2_release_target);
+}
+
 /*
  * Always get the target's kref when scheduling work on one its units.
  * Each workqueue job is responsible to call sbp2_target_put() upon return.
  */
 static void sbp2_queue_work(struct sbp2_logical_unit *lu, unsigned long delay)
 {
-	if (queue_delayed_work(sbp2_wq, &lu->work, delay))
-		kref_get(&lu->tgt->kref);
-}
-
-static void sbp2_target_put(struct sbp2_target *tgt)
-{
-	kref_put(&tgt->kref, sbp2_release_target);
+	kref_get(&lu->tgt->kref);
+	if (!queue_delayed_work(sbp2_wq, &lu->work, delay))
+		sbp2_target_put(lu->tgt);
 }
 
 static void
@@ -993,6 +1008,7 @@ static int sbp2_add_logical_unit(struct 
 
 	lu->tgt      = tgt;
 	lu->lun      = lun_entry & 0xffff;
+	lu->login_id = INVALID_LOGIN_ID;
 	lu->retries  = 0;
 	lu->has_sdev = false;
 	lu->blocked  = false;

-- 

  parent reply	other threads:[~2008-11-04 23:46 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20081104232144.186593464@mini.kroah.org>
2008-11-04 23:30 ` [patch 00/57] 2.6.27-stable review Greg KH
2008-11-04 23:30   ` [patch 01/57] agp: Fix stolen memory counting on G4X Greg KH
2008-11-04 23:30   ` [patch 02/57] SCSI: sd: Fix handling of NO_SENSE check condition Greg KH
2008-11-04 23:31   ` [patch 03/57] S390: Fix sysdev class file creation Greg KH
2008-11-04 23:31   ` [patch 04/57] sysfs: Fix return values for sysdev_store_{ulong, int} Greg KH
2008-11-04 23:31   ` [patch 05/57] ipmi: add MODULE_ALIAS to load ipmi_devintf with ipmi_si Greg KH
2008-11-04 23:31   ` [patch 06/57] USB: fix crash when URBs are unlinked after the device is gone Greg KH
2008-11-04 23:31   ` [patch 07/57] ALSA: hda - Add reboot notifier Greg KH
2008-11-04 23:31   ` [patch 08/57] kbuild: mkspec - fix build rpm Greg KH
2008-11-04 23:31   ` [patch 09/57] x86: fix /dev/mem mmap breakage when PAT is disabled Greg KH
2008-11-04 23:31   ` [patch 10/57] atl1: fix vlan tag regression Greg KH
2008-11-04 23:31   ` [patch 11/57] libertas: fix buffer overrun Greg KH
2008-11-04 23:31   ` [patch 12/57] Revert "HID: Invert HWHEEL mappings for some Logitech mice" Greg KH
2008-11-04 23:31   ` [patch 13/57] libata: initialize port_task when !CONFIG_ATA_SFF Greg KH
2008-11-04 23:31   ` [patch 14/57] syncookies: fix inclusion of tcp options in syn-ack Greg KH
2008-11-04 23:31   ` [patch 15/57] tcp: Restore ordering of TCP options for the sake of inter-operability Greg KH
2008-11-04 23:31   ` [patch 16/57] tcpv6: fix option space offsets with md5 Greg KH
2008-11-04 23:31   ` [patch 17/57] pkt_sched: sch_generic: Fix oops in sch_teql Greg KH
2008-11-04 23:31   ` [patch 18/57] sparc64: Fix race in arch/sparc64/kernel/trampoline.S Greg KH
2008-11-04 23:31   ` [patch 19/57] math-emu: Fix signalling of underflow and inexact while packing result Greg KH
2008-11-04 23:31   ` [patch 20/57] firewire: fix setting tag and sy in iso transmission Greg KH
2008-11-04 23:31   ` [patch 21/57] firewire: fix ioctl() return code Greg KH
2008-11-04 23:31   ` [patch 22/57] firewire: Survive more than 256 bus resets Greg KH
2008-11-04 23:31   ` [patch 23/57] firewire: fix struct fw_node memory leak Greg KH
2008-11-04 23:31   ` [patch 24/57] firewire: fw-sbp2: delay first login to avoid retries Greg KH
2008-11-04 23:31   ` Greg KH [this message]
2008-11-04 23:31   ` [patch 26/57] ACPI: Always report a sync event after a lid state change Greg KH
2008-11-04 23:31   ` [patch 27/57] powerpc: fix i2c on PPC linkstation / kurobox machines Greg KH
2008-11-04 23:31   ` [patch 28/57] powerpc: Reserve in bootmem lmb reserved regions that cross NUMA nodes Greg KH
2008-11-04 23:32   ` [patch 29/57] powerpc/numa: Make memory reserve code more robust Greg KH
2008-11-04 23:32   ` [patch 30/57] powerpc: Dont use a 16G page if beyond mem= limits Greg KH
2008-11-04 23:32   ` [patch 31/57] i2c: The i2c mailing list is moving Greg KH
2008-11-04 23:32   ` [patch 32/57] scx200_i2c: Add missing class parameter Greg KH
2008-11-04 23:32   ` [patch 33/57] ALSA: use correct lock in snd_ctl_dev_disconnect() Greg KH
2008-11-04 23:32   ` [patch 34/57] V4L: pvrusb2: Keep MPEG PTSs from drifting away Greg KH
2008-11-04 23:32   ` [patch 35/57] DVB: s5h1411: bugfix: Setting serial or parallel mode could destroy bits Greg KH
2008-11-04 23:32   ` [patch 36/57] DVB: s5h1411: Perform s5h1411 soft reset after tuning Greg KH
2008-11-04 23:32   ` [patch 37/57] DVB: s5h1411: Power down s5h1411 when not in use Greg KH
2008-11-04 23:32   ` [patch 38/57] PCI: fix 64-vbit prefetchable memory resource BARs Greg KH
2008-11-04 23:32   ` [patch 39/57] sched: disable the hrtick for now Greg KH
2008-11-04 23:33   ` [patch 40/57] sched_clock: prevent scd->clock from moving backwards Greg KH
2008-11-04 23:33   ` [patch 41/57] x86: avoid dereferencing beyond stack + THREAD_SIZE Greg KH
2008-11-04 23:33   ` [patch 42/57] rtc-cmos: look for PNP RTC first, then for platform RTC Greg KH
2008-11-04 23:33   ` [patch 43/57] USB: storage: Avoid I/O errors when issuing SCSI ioctls to JMicron USB/ATA bridge Greg KH
2008-11-04 23:33   ` [patch 44/57] x86: register a platform RTC device if PNP doesnt describe it Greg KH
2008-11-04 23:33   ` [patch 45/57] sata_promise: add ATA engine reset to reset ops Greg KH
2008-11-04 23:33   ` [patch 46/57] sata_nv: fix generic, nf2/3 detection regression Greg KH
2008-11-04 23:33   ` [patch 47/57] ACPI: EC: do transaction from interrupt context Greg KH
2008-11-04 23:33   ` [patch 48/57] ACPI: EC: Rename some variables Greg KH
2008-11-04 23:33   ` [patch 49/57] ACPI: EC: Check for IBF=0 periodically if not in GPE mode Greg KH
2008-11-04 23:33   ` [patch 50/57] libata: Fix LBA48 on pata_it821x RAID volumes Greg KH
2008-11-04 23:33   ` [patch 51/57] ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism Greg KH
2008-11-05  0:48     ` Zhao Yakui
2008-11-05  1:02       ` Greg KH
2008-11-04 23:33   ` [patch 52/57] ACPI: Clear WAK_STS on resume Greg KH
2008-11-04 23:33   ` [patch 53/57] Input: atkbd - expand Latitudes force release quirk to other Dells Greg KH
2008-11-04 23:33   ` [patch 54/57] hfsplus: fix Buffer overflow with a corrupted image Greg KH
2008-11-04 23:33   ` [patch 55/57] hfsplus: check read_mapping_page() return value Greg KH
2008-11-04 23:33   ` [patch 56/57] bonding: fix panic when taking bond interface down before removing module Greg KH
2008-11-04 23:33   ` [patch 57/57] file caps: always start with clear bprm->caps_* Greg KH

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