Conditional spinlocks make it hard for gcc and for lockdep to follow the code flow. This one causes a warning with at least gcc-9 and higher: In file included from include/linux/irq.h:14, from drivers/gpu/drm/i915/i915_pmu.c:7: drivers/gpu/drm/i915/i915_pmu.c: In function 'i915_sample': include/linux/spinlock.h:289:3: error: 'flags' may be used uninitialized in this function [-Werror=maybe-uninitialized] 289 | _raw_spin_unlock_irqrestore(lock, flags); \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/i915/i915_pmu.c:288:17: note: 'flags' was declared here 288 | unsigned long flags; | ^~~~~ Split out the part between the locks into a separate function for readability and to let the compiler figure out what the logic actually is. Fixes: d79e1bd676f0 ("drm/i915/pmu: Only use exclusive mmio access for gen7") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/msgid/20200527140526.1458215-1-arnd@arndb.de (cherry picked from commit 6ec81b82732e2b4a5ac0853fd33919ff1ca94238) Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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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