[PATCH 4.14 087/137] intel_th: Fix device removal logic

From: Greg Kroah-Hartman
Date: Tue Oct 02 2018 - 09:33:57 EST


4.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>

commit 8801922cd94c918e4dc3a108ecaa500c4d40583f upstream.

Commit a753bfcfdb1f ("intel_th: Make the switch allocate its subdevices")
brings in new subdevice addition/removal logic that's broken for "host
mode": the SWITCH device has no children to begin with, which is not
handled in the code. This results in a null dereference bug later down
the path.

This patch fixes the subdevice removal code to handle host mode correctly.

Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Fixes: a753bfcfdb1f ("intel_th: Make the switch allocate its subdevices")
CC: stable@xxxxxxxxxxxxxxx # v4.14+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/hwtracing/intel_th/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -147,7 +147,8 @@ static int intel_th_remove(struct device
th->thdev[i] = NULL;
}

- th->num_thdevs = lowest;
+ if (lowest >= 0)
+ th->num_thdevs = lowest;
}

if (thdrv->attr_group)