mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2025-01-27 00:04:47 +08:00
79d878f7ad
Hou Tao says: ==================== Now bpf uses RCU grace period chaining to wait for the completion of access from both sleepable and non-sleepable bpf program: calling call_rcu_tasks_trace() firstly to wait for a RCU-tasks-trace grace period, then in its callback calls call_rcu() or kfree_rcu() to wait for a normal RCU grace period. According to the implementation of RCU Tasks Trace, it inovkes ->postscan_func() to wait for one RCU-tasks-trace grace period and rcu_tasks_trace_postscan() inovkes synchronize_rcu() to wait for one normal RCU grace period in turn, so one RCU-tasks-trace grace period will imply one normal RCU grace period. To codify the implication, introduces rcu_trace_implies_rcu_gp() in patch #1. And using it in patch Other two uses of call_rcu_tasks_trace() are unchanged: for __bpf_prog_put_rcu() there is no gp chain and for __bpf_tramp_image_put_rcu_tasks() it chains RCU tasks trace GP and RCU tasks GP. An alternative way to remove these unnecessary RCU grace period chainings is using the RCU polling API to check whether or not a normal RCU grace period has passed (e.g. get_state_synchronize_rcu()). But it needs an unsigned long space for each free element or each call, and it is not affordable for local storage element, so as for now always rcu_trace_implies_rcu_gp(). Comments are always welcome. Change Log: v2: * codify the implication of RCU Tasks Trace grace period instead of assuming for it v1: https://lore.kernel.org/bpf/20221011071128.3470622-1-houtao@huaweicloud.com Hou Tao (3): bpf: Use rcu_trace_implies_rcu_gp() in bpf memory allocator bpf: Use rcu_trace_implies_rcu_gp() in local storage map bpf: Use rcu_trace_implies_rcu_gp() for program array freeing ==================== Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.