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authorAndriy Gapon <avg@FreeBSD.org>2019-06-05 13:18:00 +0000
committerAndriy Gapon <avg@FreeBSD.org>2019-06-05 13:18:00 +0000
commit2b1d0ab2f6c7b182ca571b66f9732a6eeb8c6bfd (patch)
tree3c99f4a2b0f3aa1ff8c1a796c35ba83106333b62
parent56db4ebd342f84d00ce35a1aa741c5a03d229e7d (diff)
downloadsrc-2b1d0ab2f6c7b182ca571b66f9732a6eeb8c6bfd.tar.gz
src-2b1d0ab2f6c7b182ca571b66f9732a6eeb8c6bfd.zip
first step towards enforcing must-succeed semantics for bus accessors
Unlike BUS_READ_IVAR / BUS_WRITE_IVAR, bus accessors do not have a return code. It is assumed that there is a tight coupling between a bus driver and a driver for a device on the bus with respect to instance variables that the bus defines for its children. So, the driver is supposed to have only valid accesses to the variables and, thus, the accessors must always succeed. Of course, programming errors sometimes happen. At present, such errors go completely unnoticed. The idea of this change is to start catching them. As a first step, there will be a warning about a failed accessor call. This is to give developers a heads-up. I plan to replace the printf with a KASSERT a week later, so that the warning is harder to ignore. Reviewed by: cem, imp, ian MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D20458
Notes
Notes: svn path=/head/; revision=348688
-rw-r--r--sys/sys/bus.h18
1 files changed, 16 insertions, 2 deletions
diff --git a/sys/sys/bus.h b/sys/sys/bus.h
index 76ac60498205..9fb4a6d4c38e 100644
--- a/sys/sys/bus.h
+++ b/sys/sys/bus.h
@@ -810,16 +810,30 @@ DECLARE_MODULE(name##_##busname, name##_##busname##_mod, \
static __inline type varp ## _get_ ## var(device_t dev) \
{ \
uintptr_t v; \
- BUS_READ_IVAR(device_get_parent(dev), dev, \
+ int e; \
+ e = BUS_READ_IVAR(device_get_parent(dev), dev, \
ivarp ## _IVAR_ ## ivar, &v); \
+ if (e != 0) { \
+ device_printf(dev, "failed to read ivar " \
+ __XSTRING(ivarp ## _IVAR_ ## ivar) " on bus %s, " \
+ "error = %d\n", \
+ device_get_nameunit(device_get_parent(dev)), e); \
+ } \
return ((type) v); \
} \
\
static __inline void varp ## _set_ ## var(device_t dev, type t) \
{ \
uintptr_t v = (uintptr_t) t; \
- BUS_WRITE_IVAR(device_get_parent(dev), dev, \
+ int e; \
+ e = BUS_WRITE_IVAR(device_get_parent(dev), dev, \
ivarp ## _IVAR_ ## ivar, v); \
+ if (e != 0) { \
+ device_printf(dev, "failed to write ivar " \
+ __XSTRING(ivarp ## _IVAR_ ## ivar) " on bus %s, " \
+ "error = %d\n", \
+ device_get_nameunit(device_get_parent(dev)), e); \
+ } \
}
/**