sleep_on(9) Kernel Functions sleep_on(9)NAMEsleep_on - synchronization using a condition variable
SYNOPSIS
#include <linux/sched.h>
void sleep_on(struct wait_queue**condition)
DESCRIPTION
The sleep_on function provides a means for synchronizing between pro‐
cesses and with interrupt handlers. The condition parameter is a
pointer to a pointer to the opaque wait_queue type. Initialize the con‐
dition variable to zero, then pass a pointer to it to the sleep_on
function. The basic idea is as follows:
struct wait_queue*con = 0;
[...]
sleep_on(&con);
While a process is sleeping, it is fully interruptible, no matter what
the cpu state when entering the function. The cpu state is restored on
being awakened.
If a null(0) is passed to sleep_on, it returns immediately, without
sleeping. This is a no-op.
RETURN VALUE
The sleep_on function only returns when explicitly awakened.
AVAILABILITY
Linux 1+
SEE ALSOwake_up(9)
/usr/src/linux/kernel/sched.c
AUTHOR
Stephen Williams <steve@icarus.com>
BUGS
A call to sleep_on(0) seems like an interesting way to test for and
momentarily allow interrupts, but that is not what happens.
The sleep_on function cannot be called by interrupt handlers.
The function is not atomic with the condition tests that the driver
writer might include, so the code executing the sleep_on function is
protected from interrupts. Failure to do so generally leads to race
conditions.
Linux DDI $Date:$ sleep_on(9)
