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ee5eda8ea5
a194dfe6e6("pipe: Rearrange sequence in pipe_write() to preallocate slot") changed pipe_write() to increment pipe->head in advance. IIUC to avoid the race with the post_one_notification()-like code which can add another buffer under pipe->rd_wait.lock without pipe->mutex. This is no longer necessary afterc73be61ced("pipe: Add general notification queue support"), pipe_write() checks pipe_has_watch_queue() and returns -EXDEV at the start. And can't help in any case, pipe_write() no longer takes this rd_wait.lock spinlock. Change pipe_write() to call copy_page_from_iter() first and do nothing if it fails. This way pipe_write() can't add a zero-sized buffer and we can simplify pipe_read() which currently has to take care of this very unlikely case. Also, with this patch we can probably kill eat_empty_buffer() and more "is this buffer empty" checks in fs/splice.c later. Link: https://lore.kernel.org/all/20250209150718.GA17013@redhat.com/ Signed-off-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20250210114039.GA3588@redhat.com Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Signed-off-by: Christian Brauner <brauner@kernel.org>
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 reStructuredText 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.