linux-kernel - [PATCH 2/4] swait: add the missing killable swaits

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Date:   Wed, 14 Jun 2017 15:20:15 -0700
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     gregkh@...uxfoundation.org
Cc:     mfuzzey@...keon.com, ebiederm@...ssion.com,
        dmitry.torokhov@...il.com, wagi@...om.org, dwmw2@...radead.org,
        jewalt@...innovations.com, rafal@...ecki.pl,
        arend.vanspriel@...adcom.com, rjw@...ysocki.net,
        yi1.li@...ux.intel.com, atull@...nel.org, moritz.fischer@...us.com,
        pmladek@...e.com, johannes.berg@...el.com,
        emmanuel.grumbach@...el.com, luciano.coelho@...el.com,
        kvalo@...eaurora.org, luto@...nel.org,
        torvalds@...ux-foundation.org, keescook@...omium.org,
        takahiro.akashi@...aro.org, dhowells@...hat.com, pjones@...hat.com,
        hdegoede@...hat.com, alan@...ux.intel.com, tytso@....edu,
        mtk.manpages@...il.com, paul.gortmaker@...driver.com,
        mtosatti@...hat.com, mawilcox@...rosoft.com,
        linux-api@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        "stable # 4 . 6" <stable@...r.kernel.org>
Subject: [PATCH 2/4] swait: add the missing killable swaits

Code in kernel which incorrectly used the non-killable variants could
end up having waits killed improperly. The respective killable waits
have been upstream for a while:

  o wait_for_completion_killable()
  o wait_for_completion_killable_timeout()

swait has been upstream since v4.6. Older kernels have had the
above variants in place for a long time.

Cc: stable <stable@...r.kernel.org> # 4.6
Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
---
 include/linux/swait.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/include/linux/swait.h b/include/linux/swait.h
index c1f9c62a8a50..2c700694d50a 100644
--- a/include/linux/swait.h
+++ b/include/linux/swait.h
@@ -169,4 +169,29 @@ do {									\
 	__ret;								\
 })
 
+#define __swait_event_killable(wq, condition)				\
+	___swait_event(wq, condition, TASK_KILLABLE, 0, schedule())
+
+#define swait_event_killable(wq, condition)				\
+({									\
+	int __ret = 0;							\
+	if (!(condition))						\
+		__ret = __swait_event_killable(wq, condition);		\
+	__ret;								\
+})
+
+#define __swait_event_killable_timeout(wq, condition, timeout)		\
+	___swait_event(wq, ___wait_cond_timeout(condition),		\
+		       TASK_KILLABLE, timeout,				\
+		       __ret = schedule_timeout(__ret))
+
+#define swait_event_killable_timeout(wq, condition, timeout)		\
+({									\
+	long __ret = timeout;						\
+	if (!___wait_cond_timeout(condition))				\
+		__ret = __swait_event_killable_timeout(wq,		\
+						condition, timeout);	\
+	__ret;								\
+})
+
 #endif /* _LINUX_SWAIT_H */
-- 
2.11.0