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5c6ca9d936
Add a DEFINE_FREE() clause for x509_certificate structs and use it in x509_cert_parse() and x509_key_preparse(). These are the only functions where scope-based x509_certificate allocation currently makes sense. A third user will be introduced with the forthcoming SPDM library (Security Protocol and Data Model) for PCI device authentication. Unlike most other DEFINE_FREE() clauses, this one checks for IS_ERR() instead of NULL before calling x509_free_certificate() at end of scope. That's because the "constructor" of x509_certificate structs, x509_cert_parse(), returns a valid pointer or an ERR_PTR(), but never NULL. Comparing the Assembler output before/after has shown they are identical, save for the fact that gcc-12 always generates two return paths when __cleanup() is used, one for the success case and one for the error case. In x509_cert_parse(), add a hint for the compiler that kzalloc() never returns an ERR_PTR(). Otherwise the compiler adds a gratuitous IS_ERR() check on return. Introduce an assume() macro for this which can be re-used elsewhere in the kernel to provide hints for the compiler. Suggested-by: Jonathan Cameron <Jonathan.Cameron@Huawei.com> Link: https://lore.kernel.org/all/20231003153937.000034ca@Huawei.com/ Link: https://lwn.net/Articles/934679/ Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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.