Messages in this thread | | | Date | Thu, 07 Dec 2023 09:37:03 +0100 | From | Dragan Simic <> | Subject | Re: [PATCH v2] i2c: rk3x: fix potential spinlock recursion on poll |
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On 2023-12-07 09:21, Jensen Huang wrote: > Possible deadlock scenario (on reboot): > rk3x_i2c_xfer_common(polling) > -> rk3x_i2c_wait_xfer_poll() > -> rk3x_i2c_irq(0, i2c); > --> spin_lock(&i2c->lock); > ... > <rk3x i2c interrupt> > -> rk3x_i2c_irq(0, i2c); > --> spin_lock(&i2c->lock); (deadlock here) > > Store the IRQ number and disable/enable it around the polling transfer. > This patch has been tested on NanoPC-T4.
In case you haven't already seen the related discussion linked below, please have a look. I also added more people to the list of recipients, in an attempt to make everyone aware of the different approaches to solving this issue.
https://lore.kernel.org/all/655177f4.050a0220.d85c9.3ba0@mx.google.com/T/#m6fc9c214452fec6681843e7f455978c35c6f6c8b
> Signed-off-by: Jensen Huang <jensenhuang@friendlyarm.com> > Reviewed-by: Heiko Stuebner <heiko@sntech.de> > Reviewed-by: Andi Shyti <andi.shyti@kernel.org> > --- > Changes in v2: > - Add description for member 'irq' to fix build warning > > drivers/i2c/busses/i2c-rk3x.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-rk3x.c > b/drivers/i2c/busses/i2c-rk3x.c > index a044ca0c35a1..4362db7c5789 100644 > --- a/drivers/i2c/busses/i2c-rk3x.c > +++ b/drivers/i2c/busses/i2c-rk3x.c > @@ -178,6 +178,7 @@ struct rk3x_i2c_soc_data { > * @clk: function clk for rk3399 or function & Bus clks for others > * @pclk: Bus clk for rk3399 > * @clk_rate_nb: i2c clk rate change notify > + * @irq: irq number > * @t: I2C known timing information > * @lock: spinlock for the i2c bus > * @wait: the waitqueue to wait for i2c transfer > @@ -200,6 +201,7 @@ struct rk3x_i2c { > struct clk *clk; > struct clk *pclk; > struct notifier_block clk_rate_nb; > + int irq; > > /* Settings */ > struct i2c_timings t; > @@ -1087,13 +1089,18 @@ static int rk3x_i2c_xfer_common(struct > i2c_adapter *adap, > > spin_unlock_irqrestore(&i2c->lock, flags); > > - rk3x_i2c_start(i2c); > - > if (!polling) { > + rk3x_i2c_start(i2c); > + > timeout = wait_event_timeout(i2c->wait, !i2c->busy, > msecs_to_jiffies(WAIT_TIMEOUT)); > } else { > + disable_irq(i2c->irq); > + rk3x_i2c_start(i2c); > + > timeout = rk3x_i2c_wait_xfer_poll(i2c); > + > + enable_irq(i2c->irq); > } > > spin_lock_irqsave(&i2c->lock, flags); > @@ -1310,6 +1317,8 @@ static int rk3x_i2c_probe(struct platform_device > *pdev) > return ret; > } > > + i2c->irq = irq; > + > platform_set_drvdata(pdev, i2c); > > if (i2c->soc_data->calc_timings == rk3x_i2c_v0_calc_timings) {
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