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| author |   Jeremy Kerr <jk@ozlabs.org> | 2017-02-16 12:24:09 +0800 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2017-02-16 15:32:19 +0100 |
| commit | 5d4bac9a5f4ef24b2482529bda6661a58e5b5b65 (patch) | |
| tree | 1148ff3f04d9b22f1cb859829b0472b32fa75001 /kernel/irq/spurious.c | |
| parent | genirq/msi: Add stubs for get_cached_msi_msg/pci_write_msi_msg (diff) | |
| download | linux-dev-5d4bac9a5f4ef24b2482529bda6661a58e5b5b65.tar.xz linux-dev-5d4bac9a5f4ef24b2482529bda6661a58e5b5b65.zip | |
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/spurious.c')
| -rw-r--r-- | kernel/irq/spurious.c | 4 |
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; } |