mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-01-01 02:33:57 +00:00
Linux kernel source tree
2c06479884
ioc_qos_write() and ioc_cost_model_write() are the same: 1) hold lock to read 'ioc->params' to local variable; 2) update params to local variable without lock; 3) hold lock to write local variable to 'ioc->params'; In theroy, if user updates params concurrenty, the params might be lost: t1: update params a t2: update params b spin_lock_irq(&ioc->lock); memcpy(qos, ioc->params.qos, sizeof(qos)) spin_unlock_irq(&ioc->lock); qos[a] = xxx; spin_lock_irq(&ioc->lock); memcpy(qos, ioc->params.qos, sizeof(qos)) spin_unlock_irq(&ioc->lock); qos[b] = xxx; spin_lock_irq(&ioc->lock); memcpy(ioc->params.qos, qos, sizeof(qos)); ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); spin_lock_irq(&ioc->lock); // updates of a will be lost memcpy(ioc->params.qos, qos, sizeof(qos)); ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); Althrough this is not common case, the problem can by fixed easily by holding the lock through the read, update, write process. Signed-off-by: Yu Kuai <yukuai3@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20221012094035.390056-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> |
||
|---|---|---|
| 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.