From: Lai Jiangshan Date: Mon, 27 Apr 2015 09:58:38 +0000 (+0800) Subject: workqueue: split apply_workqueue_attrs() into 3 stages X-Git-Tag: omap-for-v4.2/fixes-rc1^2~86^2~13 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d5f0764b5264d2954ba6e3deb04f4f5de8e4476;p=pandora-kernel.git workqueue: split apply_workqueue_attrs() into 3 stages Current apply_workqueue_attrs() includes pwqs-allocation and pwqs-installation, so when we batch multiple apply_workqueue_attrs()s as a transaction, we can't ensure the transaction must succeed or fail as a complete unit. To solve this, we split apply_workqueue_attrs() into three stages. The first stage does the preparation: allocation memory, pwqs. The second stage does the attrs-installaion and pwqs-installation. The third stage frees the allocated memory and (old or unused) pwqs. As the result, batching multiple apply_workqueue_attrs()s can succeed or fail as a complete unit: 1) batch do all the first stage for all the workqueues 2) only commit all when all the above succeed. This patch is a preparation for the next patch ("Allow modifying low level unbound workqueue cpumask") which will do a multiple apply_workqueue_attrs(). The patch doesn't have functionality changed except two minor adjustment: 1) free_unbound_pwq() for the error path is removed, we use the heavier version put_pwq_unlocked() instead since the error path is rare. this adjustment simplifies the code. 2) the memory-allocation is also moved into wq_pool_mutex. this is needed to avoid to do the further splitting. tj: minor updates to comments. Suggested-by: Tejun Heo Cc: Christoph Lameter Cc: Kevin Hilman Cc: Lai Jiangshan Cc: Mike Galbraith Cc: Paul E. McKenney Cc: Tejun Heo Cc: Viresh Kumar Cc: Frederic Weisbecker Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo --- Reading git-diff-tree failed