drm/i915: fix potential dangling else problems in for_each_ macros
We have serious dangling else bugs waiting to happen in our for_each_
style macros with ifs. Consider, for example,
#define for_each_power_domain(domain, mask) \
for ((domain) = 0; (domain) < POWER_DOMAIN_NUM; (domain)++) \
if ((1 << (domain)) & (mask))
If this is used in context:
if (condition)
for_each_power_domain(domain, mask);
else
foo();
foo() will be called for each domain *not* in mask, if condition holds,
and not at all if condition doesn't hold.
Fix this by reversing the conditions in the macros, and adding an else
branch for the "for each" block, so that other if/else blocks can't
interfere. Provide a "for_each_if" helper macro to make it easier to get
this right.
v2: move for_each_if to drmP.h in a separate patch.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448392916-2281-2-git-send-email-jani.nikula@intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
index e6cb252..02551ff 100644
--- a/drivers/gpu/drm/i915/intel_dsi.h
+++ b/drivers/gpu/drm/i915/intel_dsi.h
@@ -117,7 +117,7 @@
#define for_each_dsi_port(__port, __ports_mask) \
for ((__port) = PORT_A; (__port) < I915_MAX_PORTS; (__port)++) \
- if ((__ports_mask) & (1 << (__port)))
+ for_each_if ((__ports_mask) & (1 << (__port)))
static inline struct intel_dsi *enc_to_intel_dsi(struct drm_encoder *encoder)
{