From: Stephen Hemminger <stephen@networkplumber.org>
Date: Mon, 31 Jul 2017 16:48:29 -0700
Patch-mainline: v4.14-rc1
Subject: PCI: hv: Do not sleep in compose_msi_msg()
Git-commit: 80bfeeb9dd6b54ac108c884c792f0fc7d4912bee
References: fate#323887
The setup of MSI with Hyper-V host was sleeping with locks held. This
error is reported when doing SR-IOV hotplug with kernel built with lockdep:
BUG: sleeping function called from invalid context at kernel/sched/completion.c:93
in_atomic(): 1, irqs_disabled(): 1, pid: 1405, name: ip
3 locks held by ip/1405:
#0: (rtnl_mutex){+.+.+.}, at: [<ffffffff976b10bb>] rtnetlink_rcv+0x1b/0x40
#1: (&desc->request_mutex){+.+...}, at: [<ffffffff970ddd33>] __setup_irq+0xb3/0x720
#2: (&irq_desc_lock_class){-.-...}, at: [<ffffffff970ddd65>] __setup_irq+0xe5/0x720
irq event stamp: 3476
hardirqs last enabled at (3475): [<ffffffff971b3005>] get_page_from_freelist+0x225/0xc90
hardirqs last disabled at (3476): [<ffffffff978024e7>] _raw_spin_lock_irqsave+0x27/0x90
softirqs last enabled at (2446): [<ffffffffc05ef0b0>] ixgbevf_configure+0x380/0x7c0 [ixgbevf]
softirqs last disabled at (2444): [<ffffffffc05ef08d>] ixgbevf_configure+0x35d/0x7c0 [ixgbevf]
The workaround is to poll for host response instead of blocking on
completion.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Olaf Hering <ohering@suse.de>
---
drivers/pci/host/pci-hyperv.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -50,6 +50,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
+#include <linux/delay.h>
#include <linux/semaphore.h>
#include <linux/irqdomain.h>
#include <asm/irqdomain.h>
@@ -1159,7 +1160,12 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
goto free_int_desc;
}
- wait_for_completion(&comp.comp_pkt.host_event);
+ /*
+ * Since this function is called with IRQ locks held, can't
+ * do normal wait for completion; instead poll.
+ */
+ while (!try_wait_for_completion(&comp.comp_pkt.host_event))
+ udelay(100);
if (comp.comp_pkt.completion_status < 0) {
dev_err(&hbus->hdev->device,