sparse: simple conditional context tracking

This patch enables a very simple form of conditional context tracking,
namely something like

if (spin_trylock(...)) {
	[...]
	spin_unlock(...);
}

Note that
__ret = spin_trylock(...);
if (__ret) {
	[...]
	spin_unlock(...);
}

does /not/ work since that would require tracking the variable and doing
extra checks to ensure the variable isn't globally accessible or similar
which could lead to race conditions.

To declare a trylock, one uses:

int spin_trylock(...) __attribute__((conditional_context(spinlock,0,1,0)))
{...}

Note that doing this currently excludes that function itself from context
checking completely.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/symbol.h b/symbol.h
index 19beb76..50fb86a 100644
--- a/symbol.h
+++ b/symbol.h
@@ -71,7 +71,7 @@ enum keyword {
 
 struct context {
 	struct expression *context;
-	unsigned int in, out;
+	unsigned int in, out, out_false;
 	int exact;
 };