As __assign_str() no longer uses its "src" parameter, there's a check to make sure nothing depends on it being different than what was passed to __string(). It originally just compared the pointer passed to __string() with the pointer passed into __assign_str() via the "src" parameter. But there's a couple of outliers that just pass in a quoted string constant, where comparing the pointers is UB to the compiler, as the compiler is free to create multiple copies of the same string constant. Instead, just use strcmp(). It may slow down the trace event, but this will eventually be removed. Also, fix the issue of passing NULL to strcmp() by adding a WARN_ON() to make sure that both "src" and the pointer saved in __string() are either both NULL or have content, and then checking if "src" is not NULL before performing the strcmp(). Link: https://lore.kernel.org/all/CAHk-=wjxX16kWd=uxG5wzqt=aXoYDf1BgWOKk+qVmAO0zh7sjA@mail.gmail.com/ Fixes: b1afefa62ca9 ("tracing: Use strcmp() in __assign_str() WARN_ON() check") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.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.
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