From 531cfe55e20ccf3999ab87feed1c931615ddbf27 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Date: Wed, 18 Nov 2015 18:09:49 +0000 Subject: [PATCH] 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 --- sys/x86/x86/intr_machdep.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/sys/x86/x86/intr_machdep.c b/sys/x86/x86/intr_machdep.c index d81c9132dd8c..35ec99253be4 100644 --- a/sys/x86/x86/intr_machdep.c +++ b/sys/x86/x86/intr_machdep.c @@ -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); }