Messages in this thread | | | From | "Brown, Aaron F" <> | Subject | RE: [Intel-wired-lan] [PATCH] e1000: Distribute switch variables for initialization | Date | Sat, 22 Feb 2020 02:01:51 +0000 |
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> From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of > Kees Cook > Sent: Wednesday, February 19, 2020 10:23 PM > To: Kirsher, Jeffrey T <jeffrey.t.kirsher@intel.com> > Cc: intel-wired-lan@lists.osuosl.org; Alexander Potapenko > <glider@google.com>; Kees Cook <keescook@chromium.org>; linux- > kernel@vger.kernel.org > Subject: [Intel-wired-lan] [PATCH] e1000: Distribute switch variables for > initialization > > Variables declared in a switch statement before any case statements > cannot be automatically initialized with compiler instrumentation (as > they are not part of any execution flow). With GCC's proposed automatic > stack variable initialization feature, this triggers a warning (and they > don't get initialized). Clang's automatic stack variable initialization > (via CONFIG_INIT_STACK_ALL=y) doesn't throw a warning, but it also > doesn't initialize such variables[1]. Note that these warnings (or silent > skipping) happen before the dead-store elimination optimization phase, > so even when the automatic initializations are later elided in favor of > direct initializations, the warnings remain. > > To avoid these problems, move such variables into the "case" where > they're used or lift them up into the main function body. > > drivers/net/ethernet/intel/e1000/e1000_main.c: In function > ‘e1000_xmit_frame’: > drivers/net/ethernet/intel/e1000/e1000_main.c:3143:18: warning: > statement will never be executed [-Wswitch-unreachable] > 3143 | unsigned int pull_size; > | ^~~~~~~~~ > > [1] https://bugs.llvm.org/show_bug.cgi?id=44916 > > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > drivers/net/ethernet/intel/e1000/e1000_main.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-)
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
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