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53c0a58beb
The important part in sockfd_lookup_light() is avoiding needless file refcount operations, not the marginal reduction of the register pressure from not keeping a struct file pointer in the caller. Switch to use fdget()/fdpu(); with sane use of CLASS(fd) we can get a better code generation... Would be nice if somebody tested it on networking test suites (including benchmarks)... sockfd_lookup_light() does fdget(), uses sock_from_file() to get the associated socket and returns the struct socket reference to the caller, along with "do we need to fput()" flag. No matching fdput(), the caller does its equivalent manually, using the fact that sock->file points to the struct file the socket has come from. Get rid of that - have the callers do fdget()/fdput() and use sock_from_file() directly. That kills sockfd_lookup_light() and fput_light() (no users left). What's more, we can get rid of explicit fdget()/fdput() by switching to CLASS(fd, ...) - code generation does not suffer, since now fdput() inserted on "descriptor is not opened" failure exit is recognized to be a no-op by compiler. [folded a fix for braino in do_recvmmsg() caught by Simon Horman] Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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.