On Thu, Jun 30, 2022 at 6:59 AM Alexander Aring <aahringo@xxxxxxxxxx> wrote:
>
> I send this patch series as RFC because it was necessary to do a kref
> change after adding __cond_lock() to refcount_dec_and_lock()
> functionality.
Can you try something like this instead?
This is two separate patches - one for sparse, and one for the kernel.
This is only *very* lightly tested (ie I tested it on a single kernel
file that used refcount_dec_and_lock())
Linus
linearize.c | 24 ++++++++++++++++++++++--
validation/context.c | 15 +++++++++++++++
2 files changed, 37 insertions(+), 2 deletions(-)
diff --git a/linearize.c b/linearize.c
index d9aed61b..8dd005af 100644
--- a/linearize.c
+++ b/linearize.c
@@ -1537,6 +1537,8 @@ static pseudo_t linearize_call_expression(struct entrypoint *ep, struct expressi
add_one_insn(ep, insn);
if (ctype) {
+ struct basic_block *post_call = NULL;
+
FOR_EACH_PTR(ctype->contexts, context) {
int in = context->in;
int out = context->out;
@@ -1547,8 +1549,21 @@ static pseudo_t linearize_call_expression(struct entrypoint *ep, struct expressi
in = 0;
}
if (out < 0) {
- check = 0;
- out = 0;
+ struct basic_block *set_context;
+ if (retval == VOID) {
+ warning(expr->pos, "nonsensical conditional output context with no condition");
+ break;
+ }
+ if (check || in) {
+ warning(expr->pos, "nonsensical conditional input context");
+ break;
+ }
+ if (!post_call)
+ post_call = alloc_basic_block(ep, expr->pos);
+ set_context = alloc_basic_block(ep, expr->pos);
+ add_branch(ep, retval, set_context, post_call);
+ set_activeblock(ep, set_context);
+ out = -out;
}
context_diff = out - in;
if (check || context_diff) {
@@ -1560,6 +1575,11 @@ static pseudo_t linearize_call_expression(struct entrypoint *ep, struct expressi
}
} END_FOR_EACH_PTR(context);
+ if (post_call) {
+ add_goto(ep, post_call);
+ set_activeblock(ep, post_call);
+ }
+
if (ctype->modifiers & MOD_NORETURN)
add_unreachable(ep);
}
diff --git a/validation/context.c b/validation/context.c
index b9500dc7..f8962f19 100644
--- a/validation/context.c
+++ b/validation/context.c
@@ -10,6 +10,10 @@ static void r(void) __attribute__((context(1,0)))
__context__(-1);
}
+// Negative output means "conditional positive output"
+extern int cond_get(void) __attribute((context(0,-1)));
+extern void nonsensical_cond_get(void) __attribute((context(0,-1)));
+
extern int _ca(int fail);
#define ca(fail) __cond_lock(_ca(fail))
@@ -19,6 +23,17 @@ static void good_paired1(void)
r();
}
+static void good_conditional(void)
+{
+ if (cond_get())
+ r();
+}
+
+static void nonsensical_conditional(void)
+{
+ nonsensical_cond_get();
+}
+
static void good_paired2(void)
{
a();
include/linux/compiler_types.h | 2 ++
include/linux/refcount.h | 6 +++---
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index d08dfcb0ac68..4f2a819fd60a 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -24,6 +24,7 @@ static inline void __chk_io_ptr(const volatile void __iomem *ptr) { }
/* context/locking */
# define __must_hold(x) __attribute__((context(x,1,1)))
# define __acquires(x) __attribute__((context(x,0,1)))
+# define __cond_acquires(x) __attribute__((context(x,0,-1)))
# define __releases(x) __attribute__((context(x,1,0)))
# define __acquire(x) __context__(x,1)
# define __release(x) __context__(x,-1)
@@ -50,6 +51,7 @@ static inline void __chk_io_ptr(const volatile void __iomem *ptr) { }
/* context/locking */
# define __must_hold(x)
# define __acquires(x)
+# define __cond_acquires(x)
# define __releases(x)
# define __acquire(x) (void)0
# define __release(x) (void)0
diff --git a/include/linux/refcount.h b/include/linux/refcount.h
index b8a6e387f8f9..a62fcca97486 100644
--- a/include/linux/refcount.h
+++ b/include/linux/refcount.h
@@ -361,9 +361,9 @@ static inline void refcount_dec(refcount_t *r)
extern __must_check bool refcount_dec_if_one(refcount_t *r);
extern __must_check bool refcount_dec_not_one(refcount_t *r);
-extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock);
-extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock);
+extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock) __cond_acquires(lock);
+extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock) __cond_acquires(lock);
extern __must_check bool refcount_dec_and_lock_irqsave(refcount_t *r,
spinlock_t *lock,
- unsigned long *flags);
+ unsigned long *flags) __cond_acquires(lock);
#endif /* _LINUX_REFCOUNT_H */
