- 06 Mar, 2012 33 commits
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Tejun Heo authored
ioc_task_link() is used to share %current's ioc on clone. If %current->io_context is set, %current is guaranteed to have refcount on the ioc and, thus, ioc_task_link() can't fail. Replace error checking in ioc_task_link() with WARN_ON_ONCE() and make it just increment refcount and nr_tasks. -v2: Description typo fix (Vivek). Signed-off-by:
Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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Tejun Heo authored
Make the following interface updates to prepare for future ioc related changes. * create_io_context() returning ioc only works for %current because it doesn't increment ref on the ioc. Drop @task parameter from it and always assume %current. * Make create_io_context_slowpath() return 0 or -errno and rename it to create_task_io_context(). * Make ioc_create_icq() take @ioc as parameter instead of assuming that of %current. The caller, get_request(), is updated to create ioc explicitly and then pass it into ioc_create_icq(). Signed-off-by:
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Tejun Heo authored
get_request() is structured a bit unusually in that failure path is inlined in the usual flow with goto labels atop and inside it. Relocate the error path to the end of the function. This is to prepare for icq handling changes in get_request() and doesn't introduce any behavior change. Signed-off-by:
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Tejun Heo authored
Now that blkg additions / removals are always done under both q and blkcg locks, the only places RCU locking is necessary are blkg_lookup[_create]() for lookup w/o blkcg lock. This patch drops unncessary RCU locking replacing it with plain blkcg locking as necessary. * blkiocg_pre_destroy() already perform proper locking and don't need RCU. Dropped. * blkio_read_blkg_stats() now uses blkcg->lock instead of RCU read lock. This isn't a hot path. * Now unnecessary synchronize_rcu() from queue exit paths removed. This makes q->nr_blkgs unnecessary. Dropped. * RCU annotation on blkg->q removed. -v2: Vivek pointed out that blkg_lookup_create() still needs to be called under rcu_read_lock(). Updated. -v3: After the update, stats_lock locking in blkio_read_blkg_stats() shouldn't be using _irq variant as it otherwise ends up enabling irq while blkcg->lock is locked. Fixed. Signed-off-by: -
Tejun Heo authored
blkgs are chained from both blkcgs and request_queues and thus subjected to two locks - blkcg->lock and q->queue_lock. As both blkcg and q can go away anytime, locking during removal is tricky. It's currently solved by wrapping removal inside RCU, which makes the synchronization complex. There are three locks to worry about - the outer RCU, q lock and blkcg lock, and it leads to nasty subtle complications like conditional synchronize_rcu() on queue exit paths. For all other paths, blkcg lock is naturally nested inside q lock and the only exception is blkcg removal path, which is a very cold path and can be implemented as clumsy but conceptually-simple reverse double lock dancing. This patch updates blkg removal path such that blkgs are removed while holding both q and blkcg locks, which is trivial for request queue exit path - blkg_destroy_all(). The blkcg removal path, blkiocg_pre_destroy(), implements reverse double lock dancing essentially identical to ioc_release_fn(). This simplifies blkg locking - no half-dead blkgs to worry about. Now unnecessary RCU annotations will be removed by the next patch. Signed-off-by:
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Tejun Heo authored
Currently, blkg is per cgroup-queue-policy combination. This is unnatural and leads to various convolutions in partially used duplicate fields in blkg, config / stat access, and general management of blkgs. This patch make blkg's per cgroup-queue and let them serve all policies. blkgs are now created and destroyed by blkcg core proper. This will allow further consolidation of common management logic into blkcg core and API with better defined semantics and layering. As a transitional step to untangle blkg management, elvswitch and policy [de]registration, all blkgs except the root blkg are being shot down during elvswitch and bypass. This patch adds blkg_root_update() to update root blkg in place on policy change. This is hacky and racy but should be good enough as interim step until we get locking simplified and switch over to proper in-place update for all blkgs. -v2: Root blkgs need to be updated on elvswitch too and blkg_alloc() comment wasn't updated according to the function change. Fixed. Both pointed out by Vivek. -v3: v2 updated blkg_destroy_all() to invoke update_root_blkg_pd() for all policies. This freed root pd during elvswitch before the last queue finished exiting and led to oops. Directly invoke update_root_blkg_pd() only on BLKIO_POLICY_PROP from cfq_exit_queue(). This also is closer to what will be done with proper in-place blkg update. Reported by Vivek. Signed-off-by: -
Tejun Heo authored
With the previous patch to move blkg list heads and counters to request_queue and blkg, logic to manage them in both policies are almost identical and can be moved to blkcg core. This patch moves blkg link logic into blkg_lookup_create(), implements common blkg unlink code in blkg_destroy(), and updates blkg_destory_all() so that it's policy specific and can skip root group. The updated blkg_destroy_all() is now used to both clear queue for bypassing and elv switching, and release all blkgs on q exit. This patch introduces a race window where policy [de]registration may race against queue blkg clearing. This can only be a problem on cfq unload and shouldn't be a real problem in practice (and we have many other places where this race already exists). Future patches will remove these unlikely races. Signed-off-by:
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Tejun Heo authored
Currently, specific policy implementations are responsible for maintaining list and number of blkgs. This duplicates code unnecessarily, and hinders factoring common code and providing blkcg API with better defined semantics. After this patch, request_queue hosts list heads and counters and blkg has list nodes for both policies. This patch only relocates the necessary fields and the next patch will actually move management code into blkcg core. Note that request_queue->blkg_list[] and ->nr_blkgs[] are hardcoded to have 2 elements. This is to avoid include dependency and will be removed by the next patch. This patch doesn't introduce any behavior change. -v2: Now unnecessary conditional on CONFIG_BLK_CGROUP_MODULE removed as pointed out by Vivek. Signed-off-by: -
Tejun Heo authored
blkg is scheduled to be unified for all policies and thus there won't be one-to-one mapping from blkg to policy. Update stat related functions to take explicit @pol or @plid arguments and not use blkg->plid. This is painful for now but most of specific stat interface functions will be replaced with a handful of generic helpers. Signed-off-by:
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Tejun Heo authored
To prepare for unifying blkgs for different policies, make blkg->pd an array with BLKIO_NR_POLICIES elements and move blkg->conf, ->stats, and ->stats_cpu into blkg_policy_data. This patch doesn't introduce any functional difference. Signed-off-by:
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Tejun Heo authored
Currently, blkcg policy implementations manage blkg refcnt duplicating mostly identical code in both policies. This patch moves refcnt to blkg and let blkcg core handle refcnt and freeing of blkgs. * cfq blkgs now also get freed via RCU. * cfq blkgs lose RB_EMPTY_ROOT() sanity check on blkg free. If necessary, we can add blkio_exit_group_fn() to resurrect this. Signed-off-by:
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Tejun Heo authored
Currently, blkg's are embedded in private data blkcg policy private data structure and thus allocated and freed by policies. This leads to duplicate codes in policies, hinders implementing common part in blkcg core with strong semantics, and forces duplicate blkg's for the same cgroup-q association. This patch introduces struct blkg_policy_data which is a separate data structure chained from blkg. Policies specifies the amount of private data it needs in its blkio_policy_type->pdata_size and blkcg core takes care of allocating them along with blkg which can be accessed using blkg_to_pdata(). blkg can be determined from pdata using pdata_to_blkg(). blkio_alloc_group_fn() method is accordingly updated to blkio_init_group_fn(). For consistency, tg_of_blkg() and cfqg_of_blkg() are replaced with blkg_to_tg() and blkg_to_cfqg() respectively, and functions to map in the reverse direction are added. Except that policy specific data now lives in a separate data structure from blkg, this patch doesn't introduce any functional difference. This will be used to unify blkg's for different policies. Signed-off-by:
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Tejun Heo authored
Keep track of all request_queues which have blkcg initialized and turn on bypass and invoke blkcg_clear_queue() on all before making changes to blkcg policies. This is to prepare for moving blkg management into blkcg core. Note that this uses more brute force than necessary. Finer grained shoot down will be implemented later and given that policy [un]registration almost never happens on running systems (blk-throtl can't be built as a module and cfq usually is the builtin default iosched), this shouldn't be a problem for the time being. Signed-off-by:
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Tejun Heo authored
Currently block core calls directly into blk-throttle for init, drain and exit. This patch adds blkcg_{init|drain|exit}_queue() which wraps the blk-throttle functions. This is to give more control and visiblity to blkcg core layer for proper layering. Further patches will add logic common to blkcg policies to the functions. While at it, collapse blk_throtl_release() into blk_throtl_exit(). There's no reason to keep them separate. Signed-off-by: -
Tejun Heo authored
Currently, blkg points to the associated blkcg via its css_id. This unnecessarily complicates dereferencing blkcg. Let blkg hold a reference to the associated blkcg and point directly to it and disable css_id on blkio_subsys. This change requires splitting blkiocg_destroy() into blkiocg_pre_destroy() and blkiocg_destroy() so that all blkg's can be destroyed and all the blkcg references held by them dropped during cgroup removal. Signed-off-by:
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Vivek Goyal authored
blk-cgroup printing code currently assumes that there is a device/disk associated with every queue in the system, but modules like floppy, can instantiate request queues without registering disk which can lead to oops. Skip the queue/blkg which don't have dev/disk associated with them. -tj: Factored out backing_dev_info check into blkg_dev_name(). Signed-off-by:
Vivek Goyal <vgoyal@redhat.com> Signed-off-by:
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Tejun Heo authored
blkg->dev is dev_t recording the device number of the block device for the associated request_queue. It is used to identify the associated block device when printing out configuration or stats. This is redundant to begin with. A blkg is an association between a cgroup and a request_queue and it of course is possible to reach request_queue from blkg and synchronization conventions are in place for safe q dereferencing, so this shouldn't be necessary from the beginning. Furthermore, it's initialized by sscanf()ing the device name of backing_dev_info. The mind boggles. Anyways, if blkg is visible under rcu lock, we *know* that the associated request_queue hasn't gone away yet and its bdi is registered and alive - blkg can't be created for request_queue which hasn't been fully initialized and it can't go away before blkg is removed. Let stat and conf read functions get device name from blkg->q->backing_dev_info.dev and pass it down to printing functions and remove blkg->dev. Signed-off-by:
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Tejun Heo authored
Now that blkcg configuration lives in blkg's, blkio_policy_node is no longer necessary. Kill it. blkio_policy_parse_and_set() now fails if invoked for missing device and functions to print out configurations are updated to print from blkg's. cftype_blkg_same_policy() is dropped along with other policy functions for consistency. Its one line is open coded in the only user - blkio_read_blkg_stats(). -v2: Update to reflect the retry-on-bypass logic change of the previous patch. Signed-off-by: -
Tejun Heo authored
blkcg is very peculiar in that it allows setting and remembering configurations for non-existent devices by maintaining separate data structures for configuration. This behavior is completely out of the usual norms and outright confusing; furthermore, it uses dev_t number to match the configuration to devices, which is unpredictable to begin with and becomes completely unuseable if EXT_DEVT is fully used. It is wholely unnecessary - we already have fully functional userland mechanism to program devices being hotplugged which has full access to device identification, connection topology and filesystem information. Add a new struct blkio_group_conf which contains all blkcg configurations to blkio_group and let blkio_group, which can be created iff the associated device exists and is removed when the associated device goes away, carry all configurations. Note that, after this patch, all newly created blkg's will always have the default configuration (unlimited for throttling and blkcg's weight for propio). This patch makes blkio_policy_node meaningless but doesn't remove it. The next patch will. -v2: Updated to retry after short sleep if blkg lookup/creation failed due to the queue being temporarily bypassed as indicated by -EBUSY return. Pointed out by Vivek. Signed-off-by: -
Tejun Heo authored
Currently both blk-throttle and cfq-iosched implement their own blkio_group creation code in throtl_get_tg() and cfq_get_cfqg(). This patch factors out the common code into blkg_lookup_create(), which returns ERR_PTR value so that transitional failures due to queue bypass can be distinguished from other failures. * New plkio_policy_ops methods blkio_alloc_group_fn() and blkio_link_group_fn added. Both are transitional and will be removed once the blkg management code is fully moved into blk-cgroup.c. * blkio_alloc_group_fn() allocates policy-specific blkg which is usually a larger data structure with blkg as the first entry and intiailizes it. Note that initialization of blkg proper, including percpu stats, is responsibility of blk-cgroup proper. Note that default config (weight, bps...) initialization is done from this method; otherwise, we end up violating locking order between blkcg and q locks via blkcg_get_CONF() functions. * blkio_link_group_fn() is called under queue_lock and responsible for linking the blkg to the queue. blkcg side is handled by blk-cgroup proper. * The common blkg creation function is named blkg_lookup_create() and blkiocg_lookup_group() is renamed to blkg_lookup() for consistency. Also, throtl / cfq related functions are similarly [re]named for consistency. This simplifies blkcg policy implementations and enables further cleanup. -v2: Vivek noticed that blkg_lookup_create() incorrectly tested blk_queue_dead() instead of blk_queue_bypass() leading a user of the function ending up creating a new blkg on bypassing queue. This is a bug introduced while relocating bypass patches before this one. Fixed. -v3: ERR_PTR patch folded into this one. @for_root added to blkg_lookup_create() to allow creating root group on a bypassed queue during elevator switch. Signed-off-by: -
Tejun Heo authored
For root blkg, blk_throtl_init() was using throtl_alloc_tg() explicitly and cfq_init_queue() was manually initializing embedded cfqd->root_group, adding unnecessarily different code paths to blkg handling. Make both use the usual blkio_group get functions - throtl_get_tg() and cfq_get_cfqg() - for the root blkio_group too. Note that blk_throtl_init() callsite is pushed downwards in blk_alloc_queue_node() so that @q is sufficiently initialized for throtl_get_tg(). This simplifies root blkg handling noticeably for cfq and will allow further modularization of blkcg API. -v2: Vivek pointed out that using cfq_get_cfqg() won't work if CONFIG_CFQ_GROUP_IOSCHED is disabled. Fix it by factoring out initialization of base part of cfqg into cfq_init_cfqg_base() and alloc/init/free explicitly if !CONFIG_CFQ_GROUP_IOSCHED. Signed-off-by: -
Tejun Heo authored
Block cgroup policies are maintained in a linked list and, theoretically, multiple policies sharing the same policy ID are allowed. This patch temporarily restricts one policy per plid and adds blkio_policy[] array which indexes registered policy types by plid. Both the restriction and blkio_policy[] array are transitional and will be removed once API cleanup is complete. Signed-off-by:
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Tejun Heo authored
blkgio_group is association between a block cgroup and a queue for a given policy. Using opaque void * for association makes things confusing and hinders factoring of common code. Use request_queue * and, if necessary, policy id instead. This will help block cgroup API cleanup. Signed-off-by:
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Tejun Heo authored
In both blkg get functions - throtl_get_tg() and cfq_get_cfqg(), instead of obtaining blkcg of %current explicitly, let the caller specify the blkcg to use as parameter and make both functions hold on to the blkcg. This is part of block cgroup interface cleanup and will help making blkcg API more modular. Signed-off-by:
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Tejun Heo authored
rcu_read_lock() in throtl_get_tb() and cfq_get_cfqg() holds onto @blkcg while looking up blkg. For API cleanup, the next patch will make the caller responsible for determining @blkcg to look blkg from and let them specify it as a parameter. Move rcu read locking out to the callers to prepare for the change. -v2: Originally this patch was described as a fix for RCU read locking bug around @blkg, which Vivek pointed out to be incorrect. It was from misunderstanding the role of rcu locking as protecting @blkg not @blkcg. Patch description updated. Signed-off-by: -
Tejun Heo authored
Elevator switch may involve changes to blkcg policies. Implement shoot down of blkio_groups. Combined with the previous bypass updates, the end goal is updating blkcg core such that it can ensure that blkcg's being affected become quiescent and don't have any per-blkg data hanging around before commencing any policy updates. Until queues are made aware of the policies that applies to them, as an interim step, all per-policy blkg data will be shot down. * blk-throtl doesn't need this change as it can't be disabled for a live queue; however, update it anyway as the scheduled blkg unification requires this behavior change. This means that blk-throtl configuration will be unnecessarily lost over elevator switch. This oddity will be removed after blkcg learns to associate individual policies with request_queues. * blk-throtl dosen't shoot down root_tg. This is to ease transition. Unified blkg will always have persistent root group and not shooting down root_tg for now eases transition to that point by avoiding having to update td->root_tg and is safe as blk-throtl can never be disabled -v2: Vivek pointed out that group list is not guaranteed to be empty on return from clear function if it raced cgroup removal and lost. Fix it by waiting a bit and retrying. This kludge will soon be removed once locking is updated such that blkg is never in limbo state between blkcg and request_queue locks. blk-throtl no longer shoots down root_tg to avoid breaking td->root_tg. Also, Nest queue_lock inside blkio_list_lock not the other way around to avoid introduce possible deadlock via blkcg lock. -v3: blkcg_clear_queue() repositioned and renamed to blkg_destroy_all() to increase consistency with later changes. cfq_clear_queue() updated to check q->elevator before dereferencing it to avoid NULL dereference on not fully initialized queues (used by later change). Signed-off-by: -
Tejun Heo authored
Extend queue bypassing such that dying queue is always bypassing and blk-throttle is drained on bypass. With blkcg policies updated to test blk_queue_bypass() instead of blk_queue_dead(), this ensures that no bio or request is held by or going through blkcg policies on a bypassing queue. This will be used to implement blkg cleanup on elevator switches and policy changes. Signed-off-by:
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Tejun Heo authored
Rename and extend elv_queisce_start/end() to blk_queue_bypass_start/end() which are exported and supports nesting via @q->bypass_depth. Also add blk_queue_bypass() to test bypass state. This will be further extended and used for blkio_group management. Signed-off-by:
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Tejun Heo authored
elevator_ops->elevator_init_fn() has a weird return value. It returns a void * which the caller should assign to q->elevator->elevator_data and %NULL return denotes init failure. Update such that it returns integer 0/-errno and sets elevator_data directly as necessary. This makes the interface more conventional and eases further cleanup. Signed-off-by:
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Tejun Heo authored
Elevator switch tries hard to keep as much as context until new elevator is ready so that it can revert to the original state if initializing the new elevator fails for some reason. Unfortunately, with more auxiliary contexts to manage, this makes elevator init and exit paths too complex and fragile. This patch makes elevator_switch() unregister the current elevator and flush icq's before start initializing the new one. As we still keep the old elevator itself, the only difference is that we lose icq's on rare occassions of switching failure, which isn't critical at all. Note that this makes explicit elevator parameter to elevator_init_queue() and __elv_register_queue() unnecessary as they always can use the current elevator. This patch enables block cgroup cleanups. -v2: blk_add_trace_msg() prints elevator name from @new_e instead of @e->type as the local variable no longer exists. This caused build failure on CONFIG_BLK_DEV_IO_TRACE. Signed-off-by: -
Tejun Heo authored
cfq has been registering zeroed blkio_poilcy_cfq if CFQ_GROUP_IOSCHED is disabled. This fortunately doesn't collide with blk-throtl as BLKIO_POLICY_PROP is zero but is unnecessary and risky. Just don't register it if not enabled. Signed-off-by:
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Tejun Heo authored
Block cgroup core can be built as module; however, it isn't too useful as blk-throttle can only be built-in and cfq-iosched is usually the default built-in scheduler. Scheduled blkcg cleanup requires calling into blkcg from block core. To simplify that, disallow building blkcg as module by making CONFIG_BLK_CGROUP bool. If building blkcg core as module really matters, which I doubt, we can revisit it after blkcg API cleanup. -v2: Vivek pointed out that IOSCHED_CFQ was incorrectly updated to depend on BLK_CGROUP. Fixed. Signed-off-by: -
Tejun Heo authored
Currently, blk_cleanup_queue() doesn't call elv_drain_elevator() if q->elevator doesn't exist; however, bio based drivers don't have elevator initialized but can still use blk-throttle. This patch moves q->elevator test inside blk_drain_queue() such that only elv_drain_elevator() is skipped if !q->elevator. -v2: loop can have registered queue which has NULL request_fn. Make sure we don't call into __blk_run_queue() in such cases. Signed-off-by:
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- 03 Mar, 2012 1 commit
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Dan Carpenter authored
"mem" is type u8. We need parenthesis here or it screws up the pointer math probably leading to an oops. Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Cc: stable@kernel.org Acked-by:
Jeff Garzik <jgarzik@redhat.com> Signed-off-by:
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- 02 Mar, 2012 6 commits
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Alan Stern authored
This patch (as1519) fixes a bug in the block layer's disk-events polling. The polling is done by a work routine queued on the system_nrt_wq workqueue. Since that workqueue isn't freezable, the polling continues even in the middle of a system sleep transition. Obviously, polling a suspended drive for media changes and such isn't a good thing to do; in the case of USB mass-storage devices it can lead to real problems requiring device resets and even re-enumeration. The patch fixes things by creating a new system-wide, non-reentrant, freezable workqueue and using it for disk-events polling. Signed-off-by:
Alan Stern <stern@rowland.harvard.edu> CC: <stable@kernel.org> Acked-by:
Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by:
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Danny Kukawka authored
Set CommandMailbox with memset before use it. Fix for: drivers/block/DAC960.c: In function ‘DAC960_V1_EnableMemoryMailboxInterface’: arch/x86/include/asm/io.h:61:1: warning: ‘CommandMailbox.Bytes[12]’ may be used uninitialized in this function [-Wuninitialized] drivers/block/DAC960.c:1175:30: note: ‘CommandMailbox.Bytes[12]’ was declared here Signed-off-by:
Danny Kukawka <danny.kukawka@bisect.de> Signed-off-by:
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Danny Kukawka authored
Fixed compiler warning: comparison between ‘DAC960_V2_IOCTL_Opcode_T’ and ‘enum <anonymous>’ Renamed enum, added a new enum for SCSI_10.CommandOpcode in DAC960_V2_ProcessCompletedCommand(). Signed-off-by:
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Stanislaw Gruszka authored
The following situation might occur: __blkdev_get: add_disk: register_disk() get_gendisk() disk_block_events() disk->ev == NULL disk_add_events() __disk_unblock_events() disk->ev != NULL --ev->block Then we unblock events, when they are suppose to be blocked. This can trigger events related block/genhd.c warnings, but also can crash in sd_check_events() or other places. I'm able to reproduce crashes with the following scripts (with connected usb dongle as sdb disk). <snip> DEV=/dev/sdb ENABLE=/sys/bus/usb/devices/1-2/bConfigurationValue function stop_me() { for i in `jobs -p` ; do kill $i 2> /dev/null ; done exit } trap stop_me SIGHUP SIGINT SIGTERM for ((i = 0; i < 10; i++)) ; do while true; do fdisk -l $DEV 2>&1 > /dev/null ; done & done while true ; do echo 1 > $ENABLE sleep 1 echo 0 > $ENABLE done </snip> I use the script to verify patch fixing oops in sd_revalidate_disk http://marc.info/?l=linux-scsi&m=132935572512352&w=2 Without Jun'ichi Nomura patch titled "Fix NULL pointer dereference in sd_revalidate_disk" or this one, script easily crash kernel within a few seconds. With both patches applied I do not observe crash. Unfortunately after some time (dozen of minutes), script will hung in: [ 1563.906432] [<c08354f5>] schedule_timeout_uninterruptible+0x15/0x20 [ 1563.906437] [<c04532d5>] msleep+0x15/0x20 [ 1563.906443] [<c05d60b2>] blk_drain_queue+0x32/0xd0 [ 1563.906447] [<c05d6e00>] blk_cleanup_queue+0xd0/0x170 [ 1563.906454] [<c06d278f>] scsi_free_queue+0x3f/0x60 [ 1563.906459] [<c06d7e6e>] __scsi_remove_device+0x6e/0xb0 [ 1563.906463] [<c06d4aff>] scsi_forget_host+0x4f/0x60 [ 1563.906468] [<c06cd84a>] scsi_remove_host+0x5a/0xf0 [ 1563.906482] [<f7f030fb>] quiesce_and_remove_host+0x5b/0xa0 [usb_storage] [ 1563.906490] [<f7f03203>] usb_stor_disconnect+0x13/0x20 [usb_storage] Anyway I think this patch is some step forward. As drawback, I do not teardown on sysfs file create error, because I do not know how to nullify disk->ev (since it can be used). However add_disk error handling practically does not exist too, and things will work without this sysfs file, except events will not be exported to user space. Signed-off-by:Stanislaw Gruszka <sgruszka@redhat.com> Acked-by:
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Muthukumar R authored
Fix setting bio flags in drivers (sd_dif/floppy). Signed-off-by:
Muthukumar R <muthur@gmail.com> Signed-off-by:
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Jun'ichi Nomura authored
Since 2.6.39 (1196f8b8), when a driver returns -ENOMEDIUM for open(), __blkdev_get() calls rescan_partitions() to remove in-kernel partition structures and raise KOBJ_CHANGE uevent. However it ends up calling driver's revalidate_disk without open and could cause oops. In the case of SCSI: process A process B ---------------------------------------------- sys_open __blkdev_get sd_open returns -ENOMEDIUM scsi_remove_device <scsi_device torn down> rescan_partitions sd_revalidate_disk <oops> Oopses are reported here: http://marc.info/?l=linux-scsi&m=132388619710052 This patch separates the partition invalidation from rescan_partitions() and use it for -ENOMEDIUM case. Reported-by:
Huajun Li <huajun.li.lee@gmail.com> Signed-off-by:
Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Acked-by:
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