xen/events: Reduce irq_info:: Spurious_cnt storage size

To prepare for interrupt spreading reduce the storage size of
irq_info::spurious_cnt to u8 so the required flag for the spreading logic
will not increase the storage size.

Protect the usage site against overruns.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20201210194045.360198201@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-12-10 20:26:04 +01:00
parent f7a6f994b4
commit 62ebcda8a8

View File

@ -95,7 +95,7 @@ struct irq_info {
struct list_head list;
struct list_head eoi_list;
short refcnt;
short spurious_cnt;
u8 spurious_cnt;
enum xen_irq_type type; /* type */
unsigned irq;
evtchn_port_t evtchn; /* event channel */
@ -528,8 +528,10 @@ static void xen_irq_lateeoi_locked(struct irq_info *info, bool spurious)
return;
if (spurious) {
if ((1 << info->spurious_cnt) < (HZ << 2))
info->spurious_cnt++;
if ((1 << info->spurious_cnt) < (HZ << 2)) {
if (info->spurious_cnt != 0xFF)
info->spurious_cnt++;
}
if (info->spurious_cnt > 1) {
delay = 1 << (info->spurious_cnt - 2);
if (delay > HZ)