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[ Upstream commit 1898eb61fbc9703efee886d3abec27a388cf28c3 ] The ARM CCN PMU driver uses dev_warn() to complain about parameters in the user-provided perf_event_attr. This means that under normal operation (e.g. a single invocation of the perf tool), a number of messages warnings may be logged to dmesg. Tools may issue multiple syscalls to probe for feature support, and multiple applications (from multiple users) can attempt to open events simultaneously, so this is not very helpful, even if a user happens to have access to dmesg. Worse, this can push important information out of the dmesg ring buffer, and can significantly slow down syscall fuzzers, vastly increasing the time it takes to find critical bugs. Demote the dev_warn() instances to dev_dbg(), as is the case for all other PMU drivers under drivers/perf/. Users who wish to debug PMU event initialisation can enable dynamic debug to receive these messages. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Pawel Moll <pawel.moll@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.