mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-03 00:54:09 +08:00
6bc3358280
The rcu_do_batch() function extracts the ready-to-invoke callbacks from the rcu_segcblist located in the ->cblist field of the current CPU's rcu_data structure. These callbacks are first moved to a local (unsegmented) rcu_cblist. The rcu_do_batch() function then uses this rcu_cblist's ->len field to count how many CBs it has invoked, but it does so by counting that field down from zero. Finally, this function negates the value in this ->len field (resulting in a positive number) and subtracts the result from the ->len field of the current CPU's ->cblist field. Except that it is sometimes necessary for rcu_do_batch() to stop invoking callbacks mid-stream, despite there being more ready to invoke, for example, if a high-priority task wakes up. In this case the remaining not-yet-invoked callbacks are requeued back onto the CPU's ->cblist, but remain in the ready-to-invoke segment of that list. As above, the negative of the local rcu_cblist's ->len field is still subtracted from the ->len field of the current CPU's ->cblist field. The design of counting down from 0 is confusing and error-prone, plus use of a positive count will make it easier to provide a uniform and consistent API to deal with the per-segment counts that are added later in this series. For example, rcu_segcblist_extract_done_cbs() can unconditionally populate the resulting unsegmented list's ->len field during extraction. This commit therefore explicitly counts how many callbacks were executed in rcu_do_batch() itself, counting up from zero, and then uses that to update the per-CPU segcb list's ->len field, without relying on the downcounting of rcl->len from zero. Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> |
||
|---|---|---|
| .. | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||
| rcu_segcblist.c | ||
| rcu_segcblist.h | ||
| rcu.h | ||
| rcuscale.c | ||
| rcutorture.c | ||
| refscale.c | ||
| srcutiny.c | ||
| srcutree.c | ||
| sync.c | ||
| tasks.h | ||
| tiny.c | ||
| tree_exp.h | ||
| tree_plugin.h | ||
| tree_stall.h | ||
| tree.c | ||
| tree.h | ||
| update.c | ||