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pcmcia: Distribute switch variables for initialization
authorKees Cook <keescook@chromium.org>
Thu, 20 Feb 2020 06:23:08 +0000 (22:23 -0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 23 Feb 2020 19:28:12 +0000 (20:28 +0100)
commit78c244226613c938729dc5528738df6157a77dd1
tree867a379a985cbc9b0e006e4eeda2e88d7341e65c
parent78856f25510369bfdc385b867303cab6a071d13d
pcmcia: 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/char/pcmcia/cm4000_cs.c: In function â€˜monitor_card’:
drivers/char/pcmcia/cm4000_cs.c:734:17: warning: statement will never be executed [-Wswitch-unreachable]
  734 |   unsigned char flags0;
      |                 ^~~~~~

[1] https://bugs.llvm.org/show_bug.cgi?id=44916

Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200220062308.69032-1-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/char/pcmcia/cm4000_cs.c