On Fri, 21 Feb 2020, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > On Thu, Feb 20, 2020 at 04:05:17PM -0800, Kees Cook wrote: >> 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/gpu/drm/i915/display/intel_display.c: In function ‘check_digital_port_conflicts’: >> drivers/gpu/drm/i915/display/intel_display.c:12963:17: warning: statement will never be executed [-Wswitch-unreachable] >> 12963 | unsigned int port_mask; >> | ^~~~~~~~~ >> >> drivers/gpu/drm/i915/intel_pm.c: In function ‘vlv_get_fifo_size’: >> drivers/gpu/drm/i915/intel_pm.c:474:7: warning: statement will never be executed [-Wswitch-unreachable] >> 474 | u32 dsparb, dsparb2, dsparb3; >> | ^~~~~~ >> drivers/gpu/drm/i915/intel_pm.c: In function ‘vlv_atomic_update_fifo’: >> drivers/gpu/drm/i915/intel_pm.c:1997:7: warning: statement will never be executed [-Wswitch-unreachable] >> 1997 | u32 dsparb, dsparb2, dsparb3; >> | ^~~~~~ >> >> [1] https://bugs.llvm.org/show_bug.cgi?id=44916 >> >> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> >> --- >> v2: remove port_mask entirely (Ville Syrjälä) >> v1: https://lore.kernel.org/lkml/20200220062258.68854-1-keescook@xxxxxxxxxxxx >> --- >> drivers/gpu/drm/i915/display/intel_display.c | 7 ++----- >> drivers/gpu/drm/i915/intel_pm.c | 4 ++-- >> 2 files changed, 4 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c >> index 064dd99bbc49..5f8c61932e82 100644 >> --- a/drivers/gpu/drm/i915/display/intel_display.c >> +++ b/drivers/gpu/drm/i915/display/intel_display.c >> @@ -12960,7 +12960,6 @@ static bool check_digital_port_conflicts(struct intel_atomic_state *state) >> WARN_ON(!connector_state->crtc); >> >> switch (encoder->type) { >> - unsigned int port_mask; >> case INTEL_OUTPUT_DDI: >> if (WARN_ON(!HAS_DDI(to_i915(dev)))) >> break; >> @@ -12968,13 +12967,11 @@ static bool check_digital_port_conflicts(struct intel_atomic_state *state) >> case INTEL_OUTPUT_DP: >> case INTEL_OUTPUT_HDMI: >> case INTEL_OUTPUT_EDP: >> - port_mask = 1 << encoder->port; >> - >> /* the same port mustn't appear more than once */ >> - if (used_ports & port_mask) >> + if (used_ports & BIT(encoder->port)) >> ret = false; >> >> - used_ports |= port_mask; >> + used_ports |= BIT(encoder->port); > > Thanks. Looks good. > > Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Thanks for the patch and review, pushed to dinq. BR, Jani. > >> break; >> case INTEL_OUTPUT_DP_MST: >> used_mst_ports |= >> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c >> index bd2d30ecc030..17d8833787c4 100644 >> --- a/drivers/gpu/drm/i915/intel_pm.c >> +++ b/drivers/gpu/drm/i915/intel_pm.c >> @@ -469,9 +469,9 @@ static void vlv_get_fifo_size(struct intel_crtc_state *crtc_state) >> struct vlv_fifo_state *fifo_state = &crtc_state->wm.vlv.fifo_state; >> enum pipe pipe = crtc->pipe; >> int sprite0_start, sprite1_start; >> + u32 dsparb, dsparb2, dsparb3; >> >> switch (pipe) { >> - u32 dsparb, dsparb2, dsparb3; >> case PIPE_A: >> dsparb = I915_READ(DSPARB); >> dsparb2 = I915_READ(DSPARB2); >> @@ -1969,6 +1969,7 @@ static void vlv_atomic_update_fifo(struct intel_atomic_state *state, >> const struct vlv_fifo_state *fifo_state = >> &crtc_state->wm.vlv.fifo_state; >> int sprite0_start, sprite1_start, fifo_size; >> + u32 dsparb, dsparb2, dsparb3; >> >> if (!crtc_state->fifo_changed) >> return; >> @@ -1994,7 +1995,6 @@ static void vlv_atomic_update_fifo(struct intel_atomic_state *state, >> spin_lock(&uncore->lock); >> >> switch (crtc->pipe) { >> - u32 dsparb, dsparb2, dsparb3; >> case PIPE_A: >> dsparb = intel_uncore_read_fw(uncore, DSPARB); >> dsparb2 = intel_uncore_read_fw(uncore, DSPARB2); >> -- >> 2.20.1 >> >> >> -- >> Kees Cook >> _______________________________________________ >> Intel-gfx mailing list >> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx >> https://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Jani Nikula, Intel Open Source Graphics Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
