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authorJeremy Kerr <jk@ozlabs.org>2017-02-16 12:24:09 +0800
committerThomas Gleixner <tglx@linutronix.de>2017-02-16 15:32:19 +0100
commit5d4bac9a5f4ef24b2482529bda6661a58e5b5b65 (patch)
tree1148ff3f04d9b22f1cb859829b0472b32fa75001 /kernel/irq
parent2f44e29cef006a4b0a4ecf7d4c5aac7d0fbb505c (diff)
downloadlinux-5d4bac9a5f4ef24b2482529bda6661a58e5b5b65.tar.bz2
genirq: Clarify logic calculating bogus irqreturn_t values
Although irqreturn_t is an enum, we treat it (and its enumeration constants) as a bitmask. However, bad_action_ret() uses a less-than operator to determine whether an irqreturn_t falls within allowable bit values, which means we need to know the signededness of an enum type to read the logic, which is implementation-dependent. This change explicitly uses an unsigned type for the comparison. We do this instead of changing to a bitwise test, as the latter compiles to increased instructions in this hot path. It looks like we get the correct behaviour currently (bad_action_ret(-1) returns 1), so this is purely a readability fix. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Link: http://lkml.kernel.org/r/1487219049-4061-1-git-send-email-jk@ozlabs.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/spurious.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
index 5707f97a3e6a..061ba7eed4ed 100644
--- a/kernel/irq/spurious.c
+++ b/kernel/irq/spurious.c
@@ -175,7 +175,9 @@ out:
static inline int bad_action_ret(irqreturn_t action_ret)
{
- if (likely(action_ret <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
+ unsigned int r = action_ret;
+
+ if (likely(r <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
return 0;
return 1;
}