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From: "Jan Beulich" <JBeulich@suse.com>
To: xen-devel <xen-devel@lists.xenproject.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Wei Liu <wei.liu2@citrix.com>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: [PATCH 2/4] x86/IRQ: bail early from irq_guest_eoi_timer_fn() when nothing is in flight
Date: Wed, 08 May 2019 06:46:51 -0600	[thread overview]
Message-ID: <5CD2CFBB020000780022CCC6@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <5CD2CDEC020000780022CC95@prv1-mh.provo.novell.com>

There's no point entering the loop in the function in this case. Instead
there still being something in flight _after_ the loop would be an
actual problem: No timer would be running anymore for issuing the EOI
eventually, and hence this IRQ (and possibly lower priority ones) would
be blocked, perhaps indefinitely.

Issue a warning instead and prefer breaking some (presumably
misbehaving) guest over stalling perhaps the entire system.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1115,7 +1115,7 @@ static void irq_guest_eoi_timer_fn(void
 
     action = (irq_guest_action_t *)desc->action;
 
-    if ( timer_is_active(&action->eoi_timer) )
+    if ( !action->in_flight || timer_is_active(&action->eoi_timer) )
         goto out;
 
     if ( action->ack_type != ACKTYPE_NONE )
@@ -1130,8 +1130,10 @@ static void irq_guest_eoi_timer_fn(void
         }
     }
 
-    if ( action->in_flight != 0 )
-        goto out;
+    if ( action->in_flight )
+        printk(XENLOG_G_WARNING
+               "IRQ%d: %d handlers still in flight at forced EOI\n",
+               desc->irq, action->in_flight);
 
     switch ( action->ack_type )
     {





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WARNING: multiple messages have this Message-ID (diff)
From: "Jan Beulich" <JBeulich@suse.com>
To: "xen-devel" <xen-devel@lists.xenproject.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Wei Liu <wei.liu2@citrix.com>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH 2/4] x86/IRQ: bail early from irq_guest_eoi_timer_fn() when nothing is in flight
Date: Wed, 08 May 2019 06:46:51 -0600	[thread overview]
Message-ID: <5CD2CFBB020000780022CCC6@prv1-mh.provo.novell.com> (raw)
Message-ID: <20190508124651.X0RKEqH2JvzhvnPwR3aNBwjPM02J03dbWUS1zVO1vxc@z> (raw)
In-Reply-To: <5CD2CDEC020000780022CC95@prv1-mh.provo.novell.com>

There's no point entering the loop in the function in this case. Instead
there still being something in flight _after_ the loop would be an
actual problem: No timer would be running anymore for issuing the EOI
eventually, and hence this IRQ (and possibly lower priority ones) would
be blocked, perhaps indefinitely.

Issue a warning instead and prefer breaking some (presumably
misbehaving) guest over stalling perhaps the entire system.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1115,7 +1115,7 @@ static void irq_guest_eoi_timer_fn(void
 
     action = (irq_guest_action_t *)desc->action;
 
-    if ( timer_is_active(&action->eoi_timer) )
+    if ( !action->in_flight || timer_is_active(&action->eoi_timer) )
         goto out;
 
     if ( action->ack_type != ACKTYPE_NONE )
@@ -1130,8 +1130,10 @@ static void irq_guest_eoi_timer_fn(void
         }
     }
 
-    if ( action->in_flight != 0 )
-        goto out;
+    if ( action->in_flight )
+        printk(XENLOG_G_WARNING
+               "IRQ%d: %d handlers still in flight at forced EOI\n",
+               desc->irq, action->in_flight);
 
     switch ( action->ack_type )
     {





_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  parent reply	other threads:[~2019-05-08 12:46 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-08 12:39 [PATCH 0/4] x86: EOI timer corrections / improvements Jan Beulich
2019-05-08 12:39 ` [Xen-devel] " Jan Beulich
2019-05-08 12:46 ` [PATCH 1/4] x86/IRQ: don't keep EOI timer running without need Jan Beulich
2019-05-08 12:46   ` [Xen-devel] " Jan Beulich
2019-05-16 10:32   ` Roger Pau Monné
2019-05-16 10:32     ` [Xen-devel] " Roger Pau Monné
2019-05-16 10:50     ` Jan Beulich
2019-05-16 10:50       ` [Xen-devel] " Jan Beulich
2019-05-16 11:03       ` Roger Pau Monné
2019-05-16 11:03         ` [Xen-devel] " Roger Pau Monné
2019-06-05 17:04   ` Andrew Cooper
2019-06-06  8:08     ` Jan Beulich
2019-06-06  9:30       ` Andrew Cooper
2019-05-08 12:46 ` Jan Beulich [this message]
2019-05-08 12:46   ` [Xen-devel] [PATCH 2/4] x86/IRQ: bail early from irq_guest_eoi_timer_fn() when nothing is in flight Jan Beulich
2019-05-16 11:37   ` Roger Pau Monné
2019-05-16 11:37     ` [Xen-devel] " Roger Pau Monné
2019-05-16 12:02     ` Jan Beulich
2019-05-16 12:02       ` [Xen-devel] " Jan Beulich
2019-05-16 13:44       ` Roger Pau Monné
2019-05-16 13:44         ` [Xen-devel] " Roger Pau Monné
2019-06-05 17:15   ` Andrew Cooper
2019-06-06  8:17     ` Jan Beulich
2019-06-06 11:34       ` Andrew Cooper
2019-06-06 11:43         ` Jan Beulich
2019-06-06 11:45           ` Andrew Cooper
2019-05-08 12:47 ` [PATCH 3/4] x86/IRQ: relax locking in irq_guest_eoi_timer_fn() Jan Beulich
2019-05-08 12:47   ` [Xen-devel] " Jan Beulich
2019-05-16 13:48   ` Roger Pau Monné
2019-05-16 13:48     ` [Xen-devel] " Roger Pau Monné
2019-06-05 17:16   ` Andrew Cooper
2019-05-08 12:48 ` [PATCH 4/4] x86/IRQ: ACKTYPE_NONE cannot make it into irq_guest_eoi_timer_fn() Jan Beulich
2019-05-08 12:48   ` [Xen-devel] " Jan Beulich
2019-05-16 13:52   ` Roger Pau Monné
2019-05-16 13:52     ` [Xen-devel] " Roger Pau Monné
2019-05-16 14:48     ` Jan Beulich
2019-05-16 14:48       ` [Xen-devel] " Jan Beulich
2019-05-17  7:04     ` Jan Beulich
2019-05-17  7:04       ` [Xen-devel] " Jan Beulich
2019-06-05 17:18   ` Andrew Cooper

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