| Message ID | 20230704215404.11533-1-ddrokosov@sberdevices.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Neil Armstrong |
| Headers | show |
| Series | [v2] clk: meson: change usleep_range() to udelay() for atomic context | expand |
On Wed 05 Jul 2023 at 00:54, Dmitry Rokosov <ddrokosov@sberdevices.ru> wrote: > The function meson_clk_pll_enable() can be invoked under the enable_lock > spinlock from the clk core logic, which risks a kernel panic during the > usleep_range() call: > > BUG: scheduling while atomic: kworker/u4:2/36/0x00000002 > Modules linked in: g_ffs usb_f_fs libcomposite > CPU: 1 PID: 36 Comm: kworker/u4:2 Not tainted 6.4.0-rc5 #273 > Workqueue: events_unbound async_run_entry_fn > Call trace: > dump_backtrace+0x9c/0x128 > show_stack+0x20/0x38 > dump_stack_lvl+0x48/0x60 > dump_stack+0x18/0x28 > __schedule_bug+0x58/0x78 > __schedule+0x828/0xa88 > schedule+0x64/0xd8 > schedule_hrtimeout_range_clock+0xd0/0x208 > schedule_hrtimeout_range+0x1c/0x30 > usleep_range_state+0x6c/0xa8 > meson_clk_pll_enable+0x1f4/0x310 > clk_core_enable+0x78/0x200 > clk_core_enable+0x58/0x200 > clk_core_enable+0x58/0x200 > clk_core_enable+0x58/0x200 > clk_enable+0x34/0x60 > > So it is required to use the udelay() function instead of usleep_range() > for the atomic context safety. > > Fixes: b6ec400aa153 ("clk: meson: introduce new pll power-on sequence for A1 SoC family") > Reported-by: Jan Dakinevich <yvdakinevich@sberdevices.ru> > Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru> Applied, Thx > --- > Changes v2 since v1 at [1]: > - remove redundant SoB from commit msg > - drop unuseful reference to clk_core_enable() from commit msg > > Links: > [1] https://lore.kernel.org/all/20230703200404.20361-1-ddrokosov@sberdevices.ru/ > --- > drivers/clk/meson/clk-pll.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c > index 56ec2210f1ad..eef6f37c8d8d 100644 > --- a/drivers/clk/meson/clk-pll.c > +++ b/drivers/clk/meson/clk-pll.c > @@ -367,9 +367,9 @@ static int meson_clk_pll_enable(struct clk_hw *hw) > * 3. enable the lock detect module > */ > if (MESON_PARM_APPLICABLE(&pll->current_en)) { > - usleep_range(10, 20); > + udelay(10); > meson_parm_write(clk->map, &pll->current_en, 1); > - usleep_range(40, 50); > + udelay(40); > }; > > if (MESON_PARM_APPLICABLE(&pll->l_detect)) {
diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c index 56ec2210f1ad..eef6f37c8d8d 100644 --- a/drivers/clk/meson/clk-pll.c +++ b/drivers/clk/meson/clk-pll.c @@ -367,9 +367,9 @@ static int meson_clk_pll_enable(struct clk_hw *hw) * 3. enable the lock detect module */ if (MESON_PARM_APPLICABLE(&pll->current_en)) { - usleep_range(10, 20); + udelay(10); meson_parm_write(clk->map, &pll->current_en, 1); - usleep_range(40, 50); + udelay(40); }; if (MESON_PARM_APPLICABLE(&pll->l_detect)) {
The function meson_clk_pll_enable() can be invoked under the enable_lock spinlock from the clk core logic, which risks a kernel panic during the usleep_range() call: BUG: scheduling while atomic: kworker/u4:2/36/0x00000002 Modules linked in: g_ffs usb_f_fs libcomposite CPU: 1 PID: 36 Comm: kworker/u4:2 Not tainted 6.4.0-rc5 #273 Workqueue: events_unbound async_run_entry_fn Call trace: dump_backtrace+0x9c/0x128 show_stack+0x20/0x38 dump_stack_lvl+0x48/0x60 dump_stack+0x18/0x28 __schedule_bug+0x58/0x78 __schedule+0x828/0xa88 schedule+0x64/0xd8 schedule_hrtimeout_range_clock+0xd0/0x208 schedule_hrtimeout_range+0x1c/0x30 usleep_range_state+0x6c/0xa8 meson_clk_pll_enable+0x1f4/0x310 clk_core_enable+0x78/0x200 clk_core_enable+0x58/0x200 clk_core_enable+0x58/0x200 clk_core_enable+0x58/0x200 clk_enable+0x34/0x60 So it is required to use the udelay() function instead of usleep_range() for the atomic context safety. Fixes: b6ec400aa153 ("clk: meson: introduce new pll power-on sequence for A1 SoC family") Reported-by: Jan Dakinevich <yvdakinevich@sberdevices.ru> Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru> --- Changes v2 since v1 at [1]: - remove redundant SoB from commit msg - drop unuseful reference to clk_core_enable() from commit msg Links: [1] https://lore.kernel.org/all/20230703200404.20361-1-ddrokosov@sberdevices.ru/ --- drivers/clk/meson/clk-pll.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)