964987738b
Now that the codes store references to pids instead of referendes to tasks. Looking up a task for a clock instead of looking up a struct pid makes the code more difficult to verify it is correct than necessary. In posix_cpu_timers_create get_task_pid can race with release_task for threads and return a NULL pid. As put_pid and cpu_timer_task_rcu handle NULL pids just fine the code works without problems but it is an extra case to consider and keep in mind while verifying and modifying the code. There are races with de_thread to consider that only don't apply because thread clocks are only allowed for threads in the same thread_group. So instead of leaving a burden for people making modification to the code in the future return a rcu protected struct pid for the clock instead. The logic for __get_task_for_pid and lookup_task has been folded into the new function pid_for_clock with the only change being the logic has been modified from working on a task to working on a pid that will be returned. In posix_cpu_clock_get instead of calling pid_for_clock checking the result and then calling pid_task to get the task. The result of pid_for_clock is fed directly into pid_task. This is safe because pid_task handles NULL pids. As such an extra error check was unnecessary. Instead of hiding the flag that enables the special clock_gettime handling, I have made the 3 callers just pass the flag in themselves. That is less code and seems just as simple to work with as the wrapper functions. Historically the clock_gettime special case of allowing a process clock to be found by the thread id did not even exist [ |
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.