kernel.git/kernel/async.c, branch linux-2.6.32.y

Fix a dead loop in async_synchronize_full()

2013-06-10T09:42:26Z

[Fixed upstream by commits 2955b47d2c1983998a8c5915cb96884e67f7cb53 and a4683487f90bfe3049686fc5c566bdc1ad03ace6 from Dan Williams, but they are much more intrusive than this tiny fix, according to Andrew - gregkh] This patch tries to fix a dead loop in async_synchronize_full(), which could be seen when preemption is disabled on a single cpu machine. void async_synchronize_full(void) { do { async_synchronize_cookie(next_cookie); } while (!list_empty(&async_running) || ! list_empty(&async_pending)); } async_synchronize_cookie() calls async_synchronize_cookie_domain() with &async_running as the default domain to synchronize. However, there might be some works in the async_pending list from other domains. On a single cpu system, without preemption, there is no chance for the other works to finish, so async_synchronize_full() enters a dead loop. It seems async_synchronize_full() wants to synchronize all entries in all running lists(domains), so maybe we could just check the entry_count to know whether all works are finished. Currently, async_synchronize_cookie_domain() expects a non-NULL running list ( if NULL, there would be NULL pointer dereference ), so maybe a NULL pointer could be used as an indication for the functions to synchronize all works in all domains. Reported-by: Paul E. McKenney Signed-off-by: Li Zhong Tested-by: Paul E. McKenney Tested-by: Christian Kujau Cc: Andrew Morton Cc: Dan Williams Cc: Christian Kujau Cc: Andrew Morton Cc: Cong Wang Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau

async: Fix lack of boot-time console due to insufficient synchronization

2009-06-08T19:31:53Z

Our async work synchronization was broken by "async: make sure independent async domains can't accidentally entangle" (commit d5a877e8dd409d8c702986d06485c374b705d340), because it would report the wrong lowest active async ID when there was both running and pending async work. This caused things like no being able to read the root filesystem, resulting in missing console devices and inability to run 'init', causing a boot-time panic. This fixes it by properly returning the lowest pending async ID: if there is any running async work, that will have a lower ID than any pending work, and we should _not_ look at the pending work list. There were alternative patches from Jaswinder and James, but this one also cleans up the code by removing the pointless 'ret' variable and the unnecesary testing for an empty list around 'for_each_entry()' (if the list is empty, the for_each_entry() thing just won't execute). Fixes-bug: http://bugzilla.kernel.org/show_bug.cgi?id=13474 Reported-and-tested-by: Chris Clayton Cc: Jaswinder Singh Rajput Cc: James Bottomley Cc: Arjan van de Ven Signed-off-by: Linus Torvalds

async: make sure independent async domains can't accidentally entangle

2009-05-24T20:38:41Z

The problem occurs when async_synchronize_full_domain() is called when the async_pending list is not empty. This will cause lowest_running() to return the cookie of the first entry on the async_pending list, which might be nothing at all to do with the domain being asked for and thus cause the domain synchronization to wait for an unrelated domain. This can cause a deadlock if domain synchronization is used from one domain to wait for another. Fix by running over the async_pending list to see if any pending items actually belong to our domain (and return their cookies if they do). Signed-off-by: James Bottomley Signed-off-by: Arjan van de Ven Signed-off-by: Linus Torvalds

async: remove the temporary (2.6.29) "async is off by default" code

2009-03-28T20:05:30Z

Now that everyone has been able to test the async code (and it's being used in the Moblin betas by default), we can enable it by default. The various fixes needed have gone into 2.6.29 already. [With an important bugfix from Stefan Richter] Signed-off-by: Arjan van de Ven

async: use list_move_tail

2009-02-08T18:00:26Z

list.h provides a dedicated primitive for "list_del followed by list_add_tail"... list_move_tail. Signed-off-by: Arjan van de Ven Signed-off-by: Stefan Richter

async: Rename _special -> _domain for clarity.

2009-02-08T17:56:11Z

Rename the async_*_special() functions to async_*_domain(), which describes the purpose of these functions much better. [Broke up long lines to silence checkpatch] Signed-off-by: Cornelia Huck Signed-off-by: Arjan van de Ven

async: Add some documentation.

2009-02-08T17:56:11Z

Add some kerneldoc to the async interface. Signed-off-by: Cornelia Huck Signed-off-by: Arjan van de Ven

async: Handle kthread_run() return codes.

2009-02-08T17:56:10Z

If we fail to create the manager thread, fall back to non-fastboot. If we fail to create an async thread, try again after waiting for a bit. Signed-off-by: Cornelia Huck Signed-off-by: Arjan van de Ven

async: Fix running list handling.

2009-02-08T17:56:10Z

async_schedule() should pass in async_running as the running list, and run_one_entry() should put the entry to be run on the provided running list instead of always on the generic one. Reported-by: Jonathan Corbet Signed-off-by: Cornelia Huck Signed-off-by: Arjan van de Ven

kernel/async.c: fix printk warnings

2009-02-05T20:56:46Z

alpha: kernel/async.c: In function 'run_one_entry': kernel/async.c:141: warning: format '%lli' expects type 'long long int', but argument 2 has type 'async_cookie_t' kernel/async.c:149: warning: format '%lli' expects type 'long long int', but argument 2 has type 'async_cookie_t' kernel/async.c:149: warning: format '%lld' expects type 'long long int', but argument 4 has type 's64' kernel/async.c: In function 'async_synchronize_cookie_special': kernel/async.c:250: warning: format '%lli' expects type 'long long int', but argument 3 has type 's64' Cc: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds