From: Rusty Russell <rusty@rustcorp.com.au>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Jeff Garzik <jeff@garzik.org>,
Tejun Heo <htejun@gmail.com>
Subject: [PATCH 4/6] typesafe: cast_if_type to allow macros functions which take more than one type.
Date: Sun, 20 Jan 2008 20:51:42 +1100 [thread overview]
Message-ID: <200801202051.42958.rusty@rustcorp.com.au> (raw)
In-Reply-To: <200801202050.41495.rusty@rustcorp.com.au>
To create functions which can take two types, but still warn on any
other types, we need a way of casting one type and no others.
To make things more complex, it should correctly handle function args,
NULL, and be usable in initializers.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff -r e6626cc7bdc2 include/linux/compiler-gcc.h
--- a/include/linux/compiler-gcc.h Sun Jan 20 18:51:51 2008 +1100
+++ b/include/linux/compiler-gcc.h Sun Jan 20 18:57:14 2008 +1100
@@ -53,3 +53,20 @@
#define noinline __attribute__((noinline))
#define __attribute_const__ __attribute__((__const__))
#define __maybe_unused __attribute__((unused))
+
+/**
+ * cast_if_type - allow an alternate type
+ * @expr: the expression to optionally cast
+ * @oktype: the type to allow.
+ * @desttype: the type to cast to.
+ *
+ * This is used to accept a particular alternate type for an expression:
+ * because any other types will not be cast, they will cause a warning as
+ * normal.
+ *
+ * Note that the unnecessary trinary forces functions to devolve into
+ * function pointers as users expect. */
+#define cast_if_type(expr, oktype, desttype) \
+ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):NULL), \
+ oktype), \
+ (desttype)(expr), (expr))
diff -r e6626cc7bdc2 include/linux/compiler-intel.h
--- a/include/linux/compiler-intel.h Sun Jan 20 18:51:51 2008 +1100
+++ b/include/linux/compiler-intel.h Sun Jan 20 18:57:14 2008 +1100
@@ -29,3 +29,5 @@
#endif
#define uninitialized_var(x) x
+
+#define cast_if_type(expr, oktype, desttype) ((desttype)(expr))
next prev parent reply other threads:[~2008-01-20 9:52 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-20 9:46 [PATCH 0/6] RFC: Typesafe callbacks Rusty Russell
2008-01-20 9:47 ` [PATCH 1/6] typesafe: Convert stop_machine and callers Rusty Russell
2008-01-20 9:48 ` [PATCH 2/6] typesafe: kthread_create and kthread_run Rusty Russell
2008-01-20 9:50 ` [PATCH 3/6] typesafe: convert kthread users Rusty Russell
2008-01-20 9:51 ` Rusty Russell [this message]
2008-01-20 9:54 ` [PATCH 5/6] typesafe: request_irq and devm_request_irq Rusty Russell
2008-01-20 9:57 ` [PATCH 6/6] typesafe: timers Rusty Russell
2008-01-20 11:25 ` [PATCH 2/6] typesafe: kthread_create and kthread_run Jan Engelhardt
2008-01-20 12:07 ` Bert Wesarg
2008-01-20 16:24 ` Johannes Weiner
2008-01-20 16:43 ` Bert Wesarg
2008-01-20 22:04 ` Rusty Russell
2008-01-21 7:56 ` Bert Wesarg
2008-01-20 12:56 ` [PATCH 0/6] RFC: Typesafe callbacks Tejun Heo
2008-01-20 13:00 ` Tejun Heo
2008-01-20 22:17 ` Rusty Russell
2008-01-21 11:33 ` Rusty Russell
2008-01-21 12:38 ` Tejun Heo
2008-01-21 23:27 ` Rusty Russell
2008-01-21 23:57 ` Linus Torvalds
2008-01-22 7:16 ` Rusty Russell
2008-01-22 15:53 ` Linus Torvalds
2008-01-22 4:20 ` Andi Kleen
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