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Subject: svn commit: r291022 - head/sys/x86/x86
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Author: royger
Date: Wed Nov 18 18:09:49 2015
New Revision: 291022
URL: https://svnweb.freebsd.org/changeset/base/291022
Log:
x86/intr: allow mutex recursion in intr_remove_handler
This is needed so interrupt handlers can be removed while the PIC is
resuming, it was previously not possible due to intr_resume holding the
intr_table_lock and intr_remove_handler recursing on it.
Sponsored by: Citrix Systems R&D
Reviewed by: kib (previous version)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D4114
Modified:
head/sys/x86/x86/intr_machdep.c
Modified: head/sys/x86/x86/intr_machdep.c
==============================================================================
--- head/sys/x86/x86/intr_machdep.c Wed Nov 18 17:52:38 2015 (r291021)
+++ head/sys/x86/x86/intr_machdep.c Wed Nov 18 18:09:49 2015 (r291022)
@@ -197,19 +197,28 @@ int
intr_remove_handler(void *cookie)
{
struct intsrc *isrc;
- int error;
+ int error, mtx_owned;
isrc = intr_handler_source(cookie);
error = intr_event_remove_handler(cookie);
if (error == 0) {
- mtx_lock(&intr_table_lock);
+ /*
+ * Recursion is needed here so PICs can remove interrupts
+ * while resuming. It was previously not possible due to
+ * intr_resume holding the intr_table_lock and
+ * intr_remove_handler recursing on it.
+ */
+ mtx_owned = mtx_owned(&intr_table_lock);
+ if (mtx_owned == 0)
+ mtx_lock(&intr_table_lock);
isrc->is_handlers--;
if (isrc->is_handlers == 0) {
isrc->is_pic->pic_disable_source(isrc, PIC_NO_EOI);
isrc->is_pic->pic_disable_intr(isrc);
}
intrcnt_updatename(isrc);
- mtx_unlock(&intr_table_lock);
+ if (mtx_owned == 0)
+ mtx_unlock(&intr_table_lock);
}
return (error);
}