forked from luck/tmp_suning_uos_patched
06fc732c33
Impact: Fix race condition xen_mc_batch has a small preempt race where it takes the address of a percpu variable immediately before disabling interrupts, thereby leaving a small window in which we may migrate to another cpu and save the flags in the wrong percpu variable. Disable interrupts before saving the old flags in a percpu. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
#ifndef _XEN_MULTICALLS_H
|
|
#define _XEN_MULTICALLS_H
|
|
|
|
#include "xen-ops.h"
|
|
|
|
/* Multicalls */
|
|
struct multicall_space
|
|
{
|
|
struct multicall_entry *mc;
|
|
void *args;
|
|
};
|
|
|
|
/* Allocate room for a multicall and its args */
|
|
struct multicall_space __xen_mc_entry(size_t args);
|
|
|
|
DECLARE_PER_CPU(unsigned long, xen_mc_irq_flags);
|
|
|
|
/* Call to start a batch of multiple __xen_mc_entry()s. Must be
|
|
paired with xen_mc_issue() */
|
|
static inline void xen_mc_batch(void)
|
|
{
|
|
unsigned long flags;
|
|
/* need to disable interrupts until this entry is complete */
|
|
local_irq_save(flags);
|
|
__get_cpu_var(xen_mc_irq_flags) = flags;
|
|
}
|
|
|
|
static inline struct multicall_space xen_mc_entry(size_t args)
|
|
{
|
|
xen_mc_batch();
|
|
return __xen_mc_entry(args);
|
|
}
|
|
|
|
/* Flush all pending multicalls */
|
|
void xen_mc_flush(void);
|
|
|
|
/* Issue a multicall if we're not in a lazy mode */
|
|
static inline void xen_mc_issue(unsigned mode)
|
|
{
|
|
if ((paravirt_get_lazy_mode() & mode) == 0)
|
|
xen_mc_flush();
|
|
|
|
/* restore flags saved in xen_mc_batch */
|
|
local_irq_restore(x86_read_percpu(xen_mc_irq_flags));
|
|
}
|
|
|
|
/* Set up a callback to be called when the current batch is flushed */
|
|
void xen_mc_callback(void (*fn)(void *), void *data);
|
|
|
|
/*
|
|
* Try to extend the arguments of the previous multicall command. The
|
|
* previous command's op must match. If it does, then it attempts to
|
|
* extend the argument space allocated to the multicall entry by
|
|
* arg_size bytes.
|
|
*
|
|
* The returned multicall_space will return with mc pointing to the
|
|
* command on success, or NULL on failure, and args pointing to the
|
|
* newly allocated space.
|
|
*/
|
|
struct multicall_space xen_mc_extend_args(unsigned long op, size_t arg_size);
|
|
|
|
#endif /* _XEN_MULTICALLS_H */
|