* [PATCH 1/3] thunderbolt: Read DP IN adapter first two dwords in one go
2019-10-01 10:29 [PATCH 0/3] thunderbolt: Fixes for few reported issues Mika Westerberg
@ 2019-10-01 10:29 ` Mika Westerberg
2019-10-04 2:43 ` Brad Campbell
2019-10-01 10:29 ` [PATCH 2/3] thunderbolt: Fix lockdep circular locking depedency warning Mika Westerberg
` (2 subsequent siblings)
3 siblings, 1 reply; 6+ messages in thread
From: Mika Westerberg @ 2019-10-01 10:29 UTC (permalink / raw)
To: linux-kernel
Cc: Andreas Noever, Michael Jamet, Yehezkel Bernat, Mika Westerberg,
Lukas Wunner, Brad Campbell, Dominik Brodowski, Bjorn Helgaas,
Nicholas Johnson, linux-pci
When we discover existing DP tunnels the code checks whether DP IN
adapter port is enabled by calling tb_dp_port_is_enabled() before it
continues the discovery process. On Light Ridge (gen 1) controller
reading only the first dword of the DP IN config space causes subsequent
access to the same DP IN port path config space to fail or return
invalid data as can be seen in the below splat:
thunderbolt 0000:07:00.0: CFG_ERROR(0:d): Invalid config space or offset
Call Trace:
tb_cfg_read+0xb9/0xd0
__tb_path_deactivate_hop+0x98/0x210
tb_path_activate+0x228/0x7d0
tb_tunnel_restart+0x95/0x200
tb_handle_hotplug+0x30e/0x630
process_one_work+0x1b4/0x340
worker_thread+0x44/0x3d0
kthread+0xeb/0x120
? process_one_work+0x340/0x340
? kthread_park+0xa0/0xa0
ret_from_fork+0x1f/0x30
If both DP In adapter config dwords are read in one go the issue does
not reproduce. This is likely firmware bug but we can work it around by
always reading the two dwords in one go. There should be no harm for
other controllers either so can do it unconditionally.
Link: https://lkml.org/lkml/2019/8/28/160
Reported-by: Brad Campbell <lists2009@fnarfbargle.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
drivers/thunderbolt/switch.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 410bf1bceeee..8e712fbf8233 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -896,12 +896,13 @@ int tb_dp_port_set_hops(struct tb_port *port, unsigned int video,
*/
bool tb_dp_port_is_enabled(struct tb_port *port)
{
- u32 data;
+ u32 data[2];
- if (tb_port_read(port, &data, TB_CFG_PORT, port->cap_adap, 1))
+ if (tb_port_read(port, data, TB_CFG_PORT, port->cap_adap,
+ ARRAY_SIZE(data)))
return false;
- return !!(data & (TB_DP_VIDEO_EN | TB_DP_AUX_EN));
+ return !!(data[0] & (TB_DP_VIDEO_EN | TB_DP_AUX_EN));
}
/**
@@ -914,19 +915,21 @@ bool tb_dp_port_is_enabled(struct tb_port *port)
*/
int tb_dp_port_enable(struct tb_port *port, bool enable)
{
- u32 data;
+ u32 data[2];
int ret;
- ret = tb_port_read(port, &data, TB_CFG_PORT, port->cap_adap, 1);
+ ret = tb_port_read(port, data, TB_CFG_PORT, port->cap_adap,
+ ARRAY_SIZE(data));
if (ret)
return ret;
if (enable)
- data |= TB_DP_VIDEO_EN | TB_DP_AUX_EN;
+ data[0] |= TB_DP_VIDEO_EN | TB_DP_AUX_EN;
else
- data &= ~(TB_DP_VIDEO_EN | TB_DP_AUX_EN);
+ data[0] &= ~(TB_DP_VIDEO_EN | TB_DP_AUX_EN);
- return tb_port_write(port, &data, TB_CFG_PORT, port->cap_adap, 1);
+ return tb_port_write(port, data, TB_CFG_PORT, port->cap_adap,
+ ARRAY_SIZE(data));
}
/* switch utility functions */
--
2.23.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH 1/3] thunderbolt: Read DP IN adapter first two dwords in one go
2019-10-01 10:29 ` [PATCH 1/3] thunderbolt: Read DP IN adapter first two dwords in one go Mika Westerberg
@ 2019-10-04 2:43 ` Brad Campbell
0 siblings, 0 replies; 6+ messages in thread
From: Brad Campbell @ 2019-10-04 2:43 UTC (permalink / raw)
To: Mika Westerberg, linux-kernel
Cc: Andreas Noever, Michael Jamet, Yehezkel Bernat, Lukas Wunner,
Dominik Brodowski, Bjorn Helgaas, Nicholas Johnson, linux-pci
On 1/10/19 6:29 pm, Mika Westerberg wrote:
> When we discover existing DP tunnels the code checks whether DP IN
> adapter port is enabled by calling tb_dp_port_is_enabled() before it
> continues the discovery process. On Light Ridge (gen 1) controller
> reading only the first dword of the DP IN config space causes subsequent
> access to the same DP IN port path config space to fail or return
> invalid data as can be seen in the below splat:
>
> thunderbolt 0000:07:00.0: CFG_ERROR(0:d): Invalid config space or offset
> Call Trace:
> tb_cfg_read+0xb9/0xd0
> __tb_path_deactivate_hop+0x98/0x210
> tb_path_activate+0x228/0x7d0
> tb_tunnel_restart+0x95/0x200
> tb_handle_hotplug+0x30e/0x630
> process_one_work+0x1b4/0x340
> worker_thread+0x44/0x3d0
> kthread+0xeb/0x120
> ? process_one_work+0x340/0x340
> ? kthread_park+0xa0/0xa0
> ret_from_fork+0x1f/0x30
>
> If both DP In adapter config dwords are read in one go the issue does
> not reproduce. This is likely firmware bug but we can work it around by
> always reading the two dwords in one go. There should be no harm for
> other controllers either so can do it unconditionally.
>
> Link: https://lkml.org/lkml/2019/8/28/160
> Reported-by: Brad Campbell <lists2009@fnarfbargle.com>
Tested-by: Brad Campbell <lists2009@fnarfbargle.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
> drivers/thunderbolt/switch.c | 19 +++++++++++--------
> 1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> index 410bf1bceeee..8e712fbf8233 100644
> --- a/drivers/thunderbolt/switch.c
> +++ b/drivers/thunderbolt/switch.c
> @@ -896,12 +896,13 @@ int tb_dp_port_set_hops(struct tb_port *port, unsigned int video,
> */
> bool tb_dp_port_is_enabled(struct tb_port *port)
> {
> - u32 data;
> + u32 data[2];
>
> - if (tb_port_read(port, &data, TB_CFG_PORT, port->cap_adap, 1))
> + if (tb_port_read(port, data, TB_CFG_PORT, port->cap_adap,
> + ARRAY_SIZE(data)))
> return false;
>
> - return !!(data & (TB_DP_VIDEO_EN | TB_DP_AUX_EN));
> + return !!(data[0] & (TB_DP_VIDEO_EN | TB_DP_AUX_EN));
> }
>
> /**
> @@ -914,19 +915,21 @@ bool tb_dp_port_is_enabled(struct tb_port *port)
> */
> int tb_dp_port_enable(struct tb_port *port, bool enable)
> {
> - u32 data;
> + u32 data[2];
> int ret;
>
> - ret = tb_port_read(port, &data, TB_CFG_PORT, port->cap_adap, 1);
> + ret = tb_port_read(port, data, TB_CFG_PORT, port->cap_adap,
> + ARRAY_SIZE(data));
> if (ret)
> return ret;
>
> if (enable)
> - data |= TB_DP_VIDEO_EN | TB_DP_AUX_EN;
> + data[0] |= TB_DP_VIDEO_EN | TB_DP_AUX_EN;
> else
> - data &= ~(TB_DP_VIDEO_EN | TB_DP_AUX_EN);
> + data[0] &= ~(TB_DP_VIDEO_EN | TB_DP_AUX_EN);
>
> - return tb_port_write(port, &data, TB_CFG_PORT, port->cap_adap, 1);
> + return tb_port_write(port, data, TB_CFG_PORT, port->cap_adap,
> + ARRAY_SIZE(data));
> }
>
> /* switch utility functions */
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 2/3] thunderbolt: Fix lockdep circular locking depedency warning
2019-10-01 10:29 [PATCH 0/3] thunderbolt: Fixes for few reported issues Mika Westerberg
2019-10-01 10:29 ` [PATCH 1/3] thunderbolt: Read DP IN adapter first two dwords in one go Mika Westerberg
@ 2019-10-01 10:29 ` Mika Westerberg
2019-10-01 10:29 ` [PATCH 3/3] thunderbolt: Drop unnecessary read when writing LC command in Ice Lake Mika Westerberg
2019-10-08 9:15 ` [PATCH 0/3] thunderbolt: Fixes for few reported issues Mika Westerberg
3 siblings, 0 replies; 6+ messages in thread
From: Mika Westerberg @ 2019-10-01 10:29 UTC (permalink / raw)
To: linux-kernel
Cc: Andreas Noever, Michael Jamet, Yehezkel Bernat, Mika Westerberg,
Lukas Wunner, Brad Campbell, Dominik Brodowski, Bjorn Helgaas,
Nicholas Johnson, linux-pci
When lockdep is enabled, plugging Thunderbolt dock on Dominik's laptop
triggers following splat:
======================================================
WARNING: possible circular locking dependency detected
5.3.0-rc6+ #1 Tainted: G T
------------------------------------------------------
pool-/usr/lib/b/1258 is trying to acquire lock:
000000005ab0ad43 (pci_rescan_remove_lock){+.+.}, at: authorized_store+0xe8/0x210
but task is already holding lock:
00000000bfb796b5 (&tb->lock){+.+.}, at: authorized_store+0x7c/0x210
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&tb->lock){+.+.}:
__mutex_lock+0xac/0x9a0
tb_domain_add+0x2d/0x130
nhi_probe+0x1dd/0x330
pci_device_probe+0xd2/0x150
really_probe+0xee/0x280
driver_probe_device+0x50/0xc0
bus_for_each_drv+0x84/0xd0
__device_attach+0xe4/0x150
pci_bus_add_device+0x4e/0x70
pci_bus_add_devices+0x2e/0x66
pci_bus_add_devices+0x59/0x66
pci_bus_add_devices+0x59/0x66
enable_slot+0x344/0x450
acpiphp_check_bridge.part.0+0x119/0x150
acpiphp_hotplug_notify+0xaa/0x140
acpi_device_hotplug+0xa2/0x3f0
acpi_hotplug_work_fn+0x1a/0x30
process_one_work+0x234/0x580
worker_thread+0x50/0x3b0
kthread+0x10a/0x140
ret_from_fork+0x3a/0x50
-> #0 (pci_rescan_remove_lock){+.+.}:
__lock_acquire+0xe54/0x1ac0
lock_acquire+0xb8/0x1b0
__mutex_lock+0xac/0x9a0
authorized_store+0xe8/0x210
kernfs_fop_write+0x125/0x1b0
vfs_write+0xc2/0x1d0
ksys_write+0x6c/0xf0
do_syscall_64+0x50/0x180
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&tb->lock);
lock(pci_rescan_remove_lock);
lock(&tb->lock);
lock(pci_rescan_remove_lock);
*** DEADLOCK ***
5 locks held by pool-/usr/lib/b/1258:
#0: 000000003df1a1ad (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x4d/0x60
#1: 0000000095a40b02 (sb_writers#6){.+.+}, at: vfs_write+0x185/0x1d0
#2: 0000000017a7d714 (&of->mutex){+.+.}, at: kernfs_fop_write+0xf2/0x1b0
#3: 000000004f262981 (kn->count#208){.+.+}, at: kernfs_fop_write+0xfa/0x1b0
#4: 00000000bfb796b5 (&tb->lock){+.+.}, at: authorized_store+0x7c/0x210
stack backtrace:
CPU: 0 PID: 1258 Comm: pool-/usr/lib/b Tainted: G T 5.3.0-rc6+ #1
On an system using ACPI hotplug the host router gets hotplugged first and then
the firmware starts sending notifications about connected devices so the above
scenario should not happen in reality. However, after taking a second
look at commit a03e828915c0 ("thunderbolt: Serialize PCIe tunnel
creation with PCI rescan") that introduced the locking, I don't think it
is actually correct. It may have cured the symptom but probably the real
root cause was somewhere closer to PCI stack and possibly is already
fixed with recent kernels. I also tried to reproduce the original issue
with the commit reverted but could not.
So to keep lockdep happy and the code bit less complex drop calls to
pci_lock_rescan_remove()/pci_unlock_rescan_remove() in
tb_switch_set_authorized() effectively reverting a03e828915c0.
Link: https://lkml.org/lkml/2019/8/30/513
Fixes: a03e828915c0 ("thunderbolt: Serialize PCIe tunnel creation with PCI rescan")
Reported-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
drivers/thunderbolt/switch.c | 9 ---------
1 file changed, 9 deletions(-)
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 8e712fbf8233..5ea8db667e83 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -1034,13 +1034,6 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
if (sw->authorized)
goto unlock;
- /*
- * Make sure there is no PCIe rescan ongoing when a new PCIe
- * tunnel is created. Otherwise the PCIe rescan code might find
- * the new tunnel too early.
- */
- pci_lock_rescan_remove();
-
switch (val) {
/* Approve switch */
case 1:
@@ -1060,8 +1053,6 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
break;
}
- pci_unlock_rescan_remove();
-
if (!ret) {
sw->authorized = val;
/* Notify status change to the userspace */
--
2.23.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 3/3] thunderbolt: Drop unnecessary read when writing LC command in Ice Lake
2019-10-01 10:29 [PATCH 0/3] thunderbolt: Fixes for few reported issues Mika Westerberg
2019-10-01 10:29 ` [PATCH 1/3] thunderbolt: Read DP IN adapter first two dwords in one go Mika Westerberg
2019-10-01 10:29 ` [PATCH 2/3] thunderbolt: Fix lockdep circular locking depedency warning Mika Westerberg
@ 2019-10-01 10:29 ` Mika Westerberg
2019-10-08 9:15 ` [PATCH 0/3] thunderbolt: Fixes for few reported issues Mika Westerberg
3 siblings, 0 replies; 6+ messages in thread
From: Mika Westerberg @ 2019-10-01 10:29 UTC (permalink / raw)
To: linux-kernel
Cc: Andreas Noever, Michael Jamet, Yehezkel Bernat, Mika Westerberg,
Lukas Wunner, Brad Campbell, Dominik Brodowski, Bjorn Helgaas,
Nicholas Johnson, linux-pci
The read is not needed as we overwrite the returned value in the next
line anyway so drop it.
Fixes: 3cdb9446a117 ("thunderbolt: Add support for Intel Ice Lake")
Reported-by: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
drivers/thunderbolt/nhi_ops.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/drivers/thunderbolt/nhi_ops.c b/drivers/thunderbolt/nhi_ops.c
index 61cd09cef943..6795851aac95 100644
--- a/drivers/thunderbolt/nhi_ops.c
+++ b/drivers/thunderbolt/nhi_ops.c
@@ -80,7 +80,6 @@ static void icl_nhi_lc_mailbox_cmd(struct tb_nhi *nhi, enum icl_lc_mailbox_cmd c
{
u32 data;
- pci_read_config_dword(nhi->pdev, VS_CAP_19, &data);
data = (cmd << VS_CAP_19_CMD_SHIFT) & VS_CAP_19_CMD_MASK;
pci_write_config_dword(nhi->pdev, VS_CAP_19, data | VS_CAP_19_VALID);
}
--
2.23.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH 0/3] thunderbolt: Fixes for few reported issues
2019-10-01 10:29 [PATCH 0/3] thunderbolt: Fixes for few reported issues Mika Westerberg
` (2 preceding siblings ...)
2019-10-01 10:29 ` [PATCH 3/3] thunderbolt: Drop unnecessary read when writing LC command in Ice Lake Mika Westerberg
@ 2019-10-08 9:15 ` Mika Westerberg
3 siblings, 0 replies; 6+ messages in thread
From: Mika Westerberg @ 2019-10-08 9:15 UTC (permalink / raw)
To: linux-kernel
Cc: Andreas Noever, Michael Jamet, Yehezkel Bernat, Lukas Wunner,
Brad Campbell, Dominik Brodowski, Bjorn Helgaas,
Nicholas Johnson, linux-pci
On Tue, Oct 01, 2019 at 01:29:02PM +0300, Mika Westerberg wrote:
> Mika Westerberg (3):
> thunderbolt: Read DP IN adapter first two dwords in one go
> thunderbolt: Fix lockdep circular locking depedency warning
> thunderbolt: Drop unnecessary read when writing LC command in Ice Lake
Applied to thunderbolt.git/fixes.
^ permalink raw reply [flat|nested] 6+ messages in thread