From: Jiang Liu <jiang.liu@xxxxxxxxxx>
Use PCI hotplug lock to serialize hotplug operations triggered by the
pciehp driver. It solves following crash issues.
test scripts:
[root]cat offline.sh
#!/bin/bash
for((i=0;i<100000;i++))
do
`echo 0 > /sys/bus/pci/slots/16/power`
`echo 1 > /sys/bus/pci/slots/16/power`
done
[root]cat remove.sh
#!/bin/bash
for((i=0;i<100000;i++))
do
`echo 1 > /sys/bus/pci/devices/0000:0f:00.0/remove`
`echo 1 > /sys/bus/pci/rescan`
done
--------------------------------------------
CPU 11
Modules linked in: pciehp pci_hotplug ipv6 cpufreq_conservative cpufreq_userspac
Pid: 8675, comm: offline.sh Not tainted 3.4.0-rc3-yijing+ #7 Huawei Technologies
CPU 11
Modules linked in: pciehp pci_hotplug ipv6 cpufreq_conservative cpufreq_userspac
Pid: 8675, comm: offline.sh Not tainted 3.4.0-rc3-yijing+ #7 Huawei Technologies
RIP: 0010:[<ffffffff81141f90>] [<ffffffff81141f90>] sysfs_name_hash+0x17/0xaa
RSP: 0018:ffff880c1a487c60 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff880c1c230c40 RCX: ffffffffffffffff
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff880c1a487c68 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff811bd401 R11: ffff880c1a4d5d40 R12: ffff880c1babd558
R13: 0000000000000000 R14: 0000000000000000 R15: ffff880c1a487dbf
FS: 00007f00722e36f0(0000) GS:ffff880c3fce0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 0000000c1b594000 CR4: 00000000000007e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process offline.sh (pid: 8675, threadinfo ffff880c1a486000, task ffff880c1b84000
Stack:
0000000000000000 ffff880c1a487ca8 ffffffff811421fc ffff880c1a487cd8
ffff880c1c230c40 0000000000000000 0000000000000000 ffff880c1a487cb8
ffff880c1a487dbf ffff880c1a487ce8 ffffffff81140e99 ffff880c1c230c40
Call Trace:
[<ffffffff811421fc>] sysfs_find_dirent+0x78/0xd4
[<ffffffff81140e99>] sysfs_hash_and_remove+0x5e/0x8e
[<ffffffff81143ffc>] sysfs_remove_bin_file+0x12/0x14
[<ffffffff811bd030>] pci_remove_resource_files+0x30/0x6b
[<ffffffff811bd454>] pci_remove_sysfs_dev_files+0x9d/0x110
[<ffffffff811b748e>] pci_stop_bus_device+0x52/0x80
[<ffffffff811b766c>] pci_stop_and_remove_bus_device+0x11/0x21
[<ffffffffa02164ae>] pciehp_unconfigure_device+0x102/0x166 [pciehp]
[<ffffffffa0216934>] ? pciehp_get_power_status+0x33/0xc3 [pciehp]
[<ffffffffa02157aa>] pciehp_disable_slot+0x106/0x163 [pciehp]
[<ffffffffa0215866>] pciehp_sysfs_disable_slot+0x5f/0xee [pciehp]
[<ffffffffa0215649>] disable_slot+0x52/0x56 [pciehp]
[<ffffffffa01f640d>] power_write_file+0x8c/0xcd [pci_hotplug]
[<ffffffff811bf10e>] pci_slot_attr_store+0x24/0x26
[<ffffffff811417c5>] sysfs_write_file+0xdc/0x111
[<ffffffff810eb55c>] vfs_write+0xae/0x151
[<ffffffff810eb6c3>] sys_write+0x47/0x6e
[<ffffffff8131fce2>] system_call_fastpath+0x16/0x1b
Code: 48 8b 47 78 55 48 89 e5 0f b7 40 60 c9 c1 e8 0d 83 e0 01 c3 55 49 89 f8 31
RIP [<ffffffff81141f90>] sysfs_name_hash+0x17/0xaa
RSP <ffff880c1a487c60>
CR2: 0000000000000000
---[ end trace af1f0f7871dbd9bc ]---
Signed-off-by: Jiang Liu <liuj97@xxxxxxxxx>
---
drivers/pci/hotplug/pciehp.h | 2 +
drivers/pci/hotplug/pciehp_core.c | 7 ++++-
drivers/pci/hotplug/pciehp_ctrl.c | 48 +++++++++++++++++++++++++++++++++++++
drivers/pci/hotplug/pciehp_hpc.c | 1 +
4 files changed, 57 insertions(+), 1 deletions(-)
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index c8a1a27..6078eea 100644
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -117,6 +117,7 @@ struct controller {
#define BLINKINGOFF_STATE 2
#define POWERON_STATE 3
#define POWEROFF_STATE 4
+#define SHUTDOWN_STATE 5
#define ATTN_BUTTN(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_ABP)
#define POWER_CTRL(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_PCP)
@@ -160,6 +161,7 @@ void pciehp_green_led_off(struct slot *slot);
void pciehp_green_led_blink(struct slot *slot);
int pciehp_check_link_status(struct controller *ctrl);
void pciehp_release_ctrl(struct controller *ctrl);
+void pciehp_shutdown_slot(struct slot *slot);
static inline const char *slot_name(struct slot *slot)
{
diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 4ceefe3..2195f67 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -268,8 +268,11 @@ static int pciehp_probe(struct pcie_device *dev)
slot = ctrl->slot;
pciehp_get_adapter_status(slot, &occupied);
pciehp_get_power_status(slot, &poweron);
- if (occupied && pciehp_force)
+ if (occupied && pciehp_force) {
+ pci_hotplug_enter();
pciehp_enable_slot(slot);
+ pci_hotplug_exit();
+ }
/* If empty slot's power status is on, turn power off */
if (!occupied && poweron && POWER_CTRL(ctrl))
pciehp_power_off_slot(slot);
@@ -313,11 +316,13 @@ static int pciehp_resume (struct pcie_device *dev)
slot = ctrl->slot;
/* Check if slot is occupied */
+ pci_hotplug_enter();
pciehp_get_adapter_status(slot, &status);
if (status)
pciehp_enable_slot(slot);
else
pciehp_disable_slot(slot);
+ pci_hotplug_exit();
}
return 0;
}
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index 8f4d261..b83f2cc 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -31,6 +31,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
+#include <linux/delay.h>
#include <linux/pci.h>
#include "../pci.h"
#include "pciehp.h"
@@ -290,6 +291,30 @@ static void pciehp_power_thread(struct work_struct *work)
struct power_work_info *info =
container_of(work, struct power_work_info, work);
struct slot *p_slot = info->p_slot;
+ bool shutdown;
+
+ /*
+ * Break out deadlock issues caused by following scenario:
+ * Thread A:
+ * 1) acquire the PCI hotplug lock
+ * 2) remove the PCI device associated with this PCIe HPC
+ * 3) call pciehp_remove() for this PCIe HPC
+ * 4) call flush_workqueue(pciehp_wq_power) to flush queued works
+ * 5) wait until all queued works done
+ * Thread B is a workqueue worker thread:
+ * 1) call pciehp_power_thread() to handle hotplug requests
+ * 2) try to acquire the PCI hotplug lock
+ * Please refer to pciehp_shutdown_slot() for the counterpart.
+ */
+ while (!pci_hotplug_try_enter()) {
+ mutex_lock(&p_slot->lock);
+ shutdown = p_slot->state == SHUTDOWN_STATE;
+ mutex_unlock(&p_slot->lock);
+ if (shutdown)
+ goto out;
+ else
+ mdelay(1);
+ }
mutex_lock(&p_slot->lock);
switch (p_slot->state) {
@@ -315,6 +340,9 @@ static void pciehp_power_thread(struct work_struct *work)
}
mutex_unlock(&p_slot->lock);
+ pci_hotplug_exit();
+
+out:
kfree(info);
}
@@ -623,3 +651,23 @@ int pciehp_sysfs_disable_slot(struct slot *p_slot)
return retval;
}
+
+void pciehp_shutdown_slot(struct slot *slot)
+{
+ u8 getstatus;
+ struct controller *ctrl = slot->ctrl;
+
+ mutex_lock(&slot->lock);
+ slot->state = SHUTDOWN_STATE;
+ mutex_unlock(&slot->lock);
+
+ if (ATTN_LED(ctrl))
+ pciehp_set_attention_status(slot, 0);
+ if (PWR_LED(ctrl)) {
+ pciehp_get_power_status(slot, &getstatus);
+ if (getstatus)
+ pciehp_green_led_on(slot);
+ else
+ pciehp_green_led_off(slot);
+ }
+}
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index d5c826d..c492b2c 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -902,6 +902,7 @@ static void pcie_cleanup_slot(struct controller *ctrl)
*/
flush_workqueue(pciehp_wq_event);
cancel_delayed_work_sync(&slot->work);
+ pciehp_shutdown_slot(slot);
flush_workqueue(pciehp_wq_power);
kfree(slot);
--
1.7.5.4
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