48628ec96d
[ Upstream commit 9b1c0c0e25dcccafd30e7d4c150c249cc65550eb ]
Fix a logical error in tty reading. We get 0 and errno == EAGAIN
on the first attempt to read from a closed file descriptor.
Compared to that a true EAGAIN is EAGAIN and -1.
If we check errno for EAGAIN first, before checking the return
value we miss the fact that the descriptor is closed.
This bug is as old as the driver. It was not showing up with
the original POLL based IRQ controller, because it was
producing multiple events. Switching to EPOLL unmasked it.
Fixes: ff6a17989c08 ("Epoll based IRQ controller")
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@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 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.