drivers/gpu/drm/drm_rect.c
134 static int drm_calc_scale(int src, int dst)
135 {
136 int scale = 0;
137
138 if (WARN_ON(src < 0 || dst < 0))
^^^^^^^^^^^^^^^^^^^^^^^^^^^
These days, with automated fuzz testing, this WARN_ON() is problematic.
WARN() is considered a kernel bug, and pr_warn() is the hip new way to
alert the user about issues.
It should probably pr_warn_once() because this is easy to trigger.
There is a kunit test which triggers it:
drivers/gpu/drm/tests/drm_rect_test.c
Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
139 return -EINVAL;
140
141 if (dst == 0)
142 return 0;
143
144 if (src > (dst << 16))
145 return DIV_ROUND_UP(src, dst);
146 else
147 scale = src / dst;
148
149 return scale;
150 }
The stack trace is:
[ 1297.757480] WARNING: CPU: 0 PID: 1555 at drivers/gpu/drm/drm_rect.c:138 drm_rect_calc_hscale+0xcc/0xd8
[ 1297.758551] Modules linked in:
[ 1297.759247] CPU: 0 PID: 1555 Comm: kunit_try_catch Tainted: G B N 6.5.1-rc1 #1
[ 1297.760085] Hardware name: Generic DT based system
[ 1297.760619] unwind_backtrace from show_stack+0x18/0x1c
[ 1297.761257] show_stack from dump_stack_lvl+0x58/0x70
[ 1297.761936] dump_stack_lvl from __warn+0xa8/0x180
[ 1297.762536] __warn from warn_slowpath_fmt+0x110/0x1dc
[ 1297.762901] warn_slowpath_fmt from drm_rect_calc_hscale+0xcc/0xd8
[ 1297.763241] drm_rect_calc_hscale from drm_test_rect_calc_hscale+0xb0/0x150
[ 1297.763608] drm_test_rect_calc_hscale from kunit_generic_run_threadfn_adapter+0x2c/0x48
[ 1297.764020] kunit_generic_run_threadfn_adapter from kthread+0x184/0x1a8
[ 1297.764384] kthread from ret_from_fork+0x14/0x2c
[ 1297.764812] Exception stack(0xfa41bfb0 to 0xfa41bff8)
[ 1297.765470] bfa0: 00000000 00000000 00000000 00000000
[ 1297.767825] bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 1297.768452] bfe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 1297.769652] ---[ end trace 0000000000000000 ]---
regards,
dan carpenter
