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LKML: Thomas Gleixner: Re: [patch V3a 17/18] posix-timers: Provide a mechanism to allocate a given timer ID
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With the prctl() it takes 3 microseconds.<br />>> > <br />>> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de><br />>> <br />>> Reviewed-by: Frederic Weisbecker <frederic@kernel.org><br />><br />> One thing which just popped up in my head -- this interface may be used not<br />> only by criu but any application which wants to create timer with specified<br />> id (hell know why, but whatever). As far as I understand we don't provide<br /><br />Sure. Application developers are creative :)<br /><br />> an interface to _read_ this property, don't we? Thus criu will restore such<br />> application which already has this bit set incorrectly.<br /><br />Delta patch below.<br /><br />Thanks,<br /><br /> tglx<br />---<br />--- a/include/uapi/linux/prctl.h<br />+++ b/include/uapi/linux/prctl.h<br />@@ -362,5 +362,6 @@ struct prctl_mm_map {<br /> #define PR_TIMER_CREATE_RESTORE_IDS 77<br /> # define PR_TIMER_CREATE_RESTORE_IDS_OFF 0<br /> # define PR_TIMER_CREATE_RESTORE_IDS_ON 1<br />+# define PR_TIMER_CREATE_RESTORE_IDS_GET 2<br /> <br /> #endif /* _LINUX_PRCTL_H */<br />--- a/kernel/time/posix-timers.c<br />+++ b/kernel/time/posix-timers.c<br />@@ -391,11 +391,17 @@ static enum hrtimer_restart posix_timer_<br /> <br /> long posixtimer_create_prctl(unsigned long ctrl)<br /> {<br />- if (ctrl > PR_TIMER_CREATE_RESTORE_IDS_ON)<br />- return -EINVAL;<br />-<br />- current->signal->timer_create_restore_ids = ctrl == PR_TIMER_CREATE_RESTORE_IDS_ON;<br />- return 0;<br />+ switch (ctrl) {<br />+ case PR_TIMER_CREATE_RESTORE_IDS_OFF:<br />+ current->signal->timer_create_restore_ids = 0;<br />+ return 0;<br />+ case PR_TIMER_CREATE_RESTORE_IDS_ON:<br />+ current->signal->timer_create_restore_ids = 0;<br />+ return 0;<br />+ case PR_TIMER_CREATE_RESTORE_IDS_GET:<br />+ return current->signal->timer_create_restore_ids;<br />+ }<br />+ return -EINVAL;<br /> }<br /> <br /> static struct pid *good_sigevent(sigevent_t * event)<br /></pre></td><td width="32" rowspan="2" class="c" valign="top"><img src="/images/icornerr.gif" width="32" height="32" alt="\" /></td></tr><tr><td align="right" valign="bottom"> 聽 </td></tr><tr><td align="right" valign="bottom">聽</td><td class="c" valign="bottom" style="padding-bottom: 0px"><img src="/images/bcornerl.gif" width="32" height="32" alt="\" /></td><td class="c">聽</td><td class="c" valign="bottom" style="padding-bottom: 0px"><img src="/images/bcornerr.gif" width="32" height="32" alt="/" /></td></tr><tr><td align="right" valign="top" colspan="2"> 聽 </td><td class="lm">Last update: 2025-03-12 12:25 聽聽 [W:2.080 / U:0.143 seconds]<br />漏2003-2020 <a href="http://blog.jasper.es/"><span itemprop="editor">Jasper Spaans</span></a>|hosted at <a href="https://www.digitalocean.com/?refcode=9a8e99d24cf9">Digital Ocean</a> and my Meterkast|<a href="http://blog.jasper.es/categories.html#lkml-ref">Read the blog</a></td><td>聽</td></tr></table><script language="javascript" src="/js/styleswitcher.js" type="text/javascript"></script></body></html>