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57 lines
2.1 KiB
Diff
57 lines
2.1 KiB
Diff
From 2b22889f68666a97d5ff3eb760cc5c486619b927 Mon Sep 17 00:00:00 2001
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From: Dexuan Cui <decui@microsoft.com>
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Date: Sun, 26 Mar 2017 16:42:20 +0800
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Subject: [PATCH 10/12] vmbus: fix missed ring events on boot
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During initialization, the channel initialization code schedules the
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tasklet to scan the VMBUS receive event page (i.e. simulates an
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interrupt). The problem was that it invokes the tasklet on a different
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CPU from where it normally runs and therefore if an event is present,
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it will clear the bit but not find the associated channel.
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This can lead to missed events, typically stuck tasks, during bootup
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when sub channels are being initialized. Typically seen as stuck
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boot with 8 or more CPU's.
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This patch is not necessary for upstream (4.11 and later) since
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commit 631e63a9f346 ("vmbus: change to per channel tasklet").
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This changed vmbus code to get rid of common tasklet which
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caused the problem.
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Cc: stable@vger.kernel.org
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Fixes: 638fea33aee8 ("Drivers: hv: vmbus: fix the race when querying & updating the percpu list")
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Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
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Origin: git@github.com:dcui/linux.git
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(cherry picked from commit 5cf3a72a111cecc7da759542c56560ce509159d7)
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---
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drivers/hv/channel_mgmt.c | 13 +++++++++++--
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1 file changed, 11 insertions(+), 2 deletions(-)
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diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
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index 095dd37367de..effac8042dc6 100644
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--- a/drivers/hv/channel_mgmt.c
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+++ b/drivers/hv/channel_mgmt.c
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@@ -388,8 +388,17 @@ void hv_event_tasklet_enable(struct vmbus_channel *channel)
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tasklet = hv_context.event_dpc[channel->target_cpu];
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tasklet_enable(tasklet);
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- /* In case there is any pending event */
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- tasklet_schedule(tasklet);
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+ /*
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+ * In case there is any pending event schedule a rescan
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+ * but must be on the correct CPU for the channel.
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+ */
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+ if (channel->target_cpu == get_cpu())
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+ tasklet_schedule(tasklet);
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+ else
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+ smp_call_function_single(channel->target_cpu,
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+ (smp_call_func_t)tasklet_schedule,
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+ tasklet, false);
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+ put_cpu();
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}
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void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)
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--
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2.16.0
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