3rd-party/linux-kernel-module-cheat
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timer: move doc to README

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Ciro Santilli
2018-07-07 19:23:04 +01:00
parent 7d16a5c024
commit f59ca5a214
4 changed files with 39 additions and 29 deletions
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3
kernel_module/README.adoc
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@@ -1,4 +1 @@
https://github.com/cirosantilli/linux-kernel-module-cheat#directory-structure
. Asynchronous
.. link:timer.c[]

20
kernel_module/timer.c
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@@ -1,22 +1,11 @@
/*
Print the jiffies every second.
Timers are callbacks that run when an interrupt happens, from the interrupt context itself.
Therefore they produce more accurate timing than thread scheduling, which is more complex,
but you can't do too much work inside of them.
See also:
- http://stackoverflow.com/questions/10812858/timers-in-linux-device-drivers
- https://gist.github.com/yagihiro/310149
*/
/* https://github.com/cirosantilli/linux-kernel-module-cheat#timers */
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/timer.h>
static int i;
/* We would normally mark this as static and give it a more generic name.
* But let's do it like this this time for the sake of our GDB kernel module step debugging example. */
void lkmc_timer_callback(struct timer_list *data);
@@ -26,7 +15,10 @@ DEFINE_TIMER(mytimer, lkmc_timer_callback);
void lkmc_timer_callback(struct timer_list *data)
{
pr_info("%u\n", (unsigned)jiffies);
pr_info("%d\n", i);
i++;
if (i == 10)
i = 0;
mod_timer(&mytimer, jiffies + onesec);
}

2
kernel_module/workqueue_cheat.c
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@@ -1,4 +1,4 @@
/* https://github.com/cirosantilli/linux-kernel-module-cheat#workqueue */
/* https://github.com/cirosantilli/linux-kernel-module-cheat#workqueues */
#include <linux/delay.h> /* usleep_range */
#include <linux/kernel.h>