Re: [PATCH] tpm/tpm_tis: Free IRQ if probing fails

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Hi,

On 4/14/20 6:45 PM, Jarkko Sakkinen wrote:
On Tue, Apr 14, 2020 at 07:04:07PM +0300, Jarkko Sakkinen wrote:
On Tue, Apr 14, 2020 at 10:26:32AM +0200, Hans de Goede wrote:
Hi,

On 4/14/20 9:13 AM, Jarkko Sakkinen wrote:
On Mon, Apr 13, 2020 at 08:11:15PM +0200, Hans de Goede wrote:
Hi,

On 4/13/20 8:07 PM, Jarkko Sakkinen wrote:
On Mon, Apr 13, 2020 at 12:04:25PM +0200, Hans de Goede wrote:
Hi Jarkko,

On 4/12/20 7:04 PM, Jarkko Sakkinen wrote:
Call devm_free_irq() if we have to revert to polling in order not to
unnecessarily reserve the IRQ for the life-cycle of the driver.

Cc: stable@xxxxxxxxxxxxxxx # 4.5.x
Reported-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Fixes: e3837e74a06d ("tpm_tis: Refactor the interrupt setup")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
     drivers/char/tpm/tpm_tis_core.c | 5 ++++-
     1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 27c6ca031e23..ae6868e7b696 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1062,9 +1062,12 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
     		if (irq) {
     			tpm_tis_probe_irq_single(chip, intmask, IRQF_SHARED,
     						 irq);
-			if (!(chip->flags & TPM_CHIP_FLAG_IRQ))
+			if (!(chip->flags & TPM_CHIP_FLAG_IRQ)) {
     				dev_err(&chip->dev, FW_BUG
     					"TPM interrupt not working, polling instead\n");
+				devm_free_irq(chip->dev.parent, priv->irq,
+					      chip);
+			}

My initial plan was actually to do something similar, but if the probe code
is actually ever fixed to work as intended again then this will lead to a
double free as then the IRQ-test path of tpm_tis_send() will have called
disable_interrupts() which already calls devm_free_irq().

You could check for chip->irq != 0 here to avoid that.

Erm in case you haven't figured it out yet this should be priv->irq != 0, sorry.

Yup.


But it all is rather messy, which is why I went with the "#if 0" approach
in my patch.

I think it is right way to fix it. It is a bug independent of the issue
we are experiencing.

However, what you are suggesting should be done in addition. Do you have
a patch in place or do you want me to refine mine?

I do not have a patch ready for this, if you can refine yours that would
be great.

Thanks! Just wanted to confirm.

And thank you for working on a (temporary?) fix for this.

As far as I see it, it is orthogonal fix that needs to be backported
to stable kernels. This bug predates the issue we're seeing now.

Hey, I came to other thoughts on "how". Would probably make sense
to always call disable_interrupts() aka no sense to add two separate
code paths. What do you think?

Sounds good, I guess it would be best to combine that with a:

	if (priv->irq == 0)
		return;

At the top of disable_interrupts() and then unconditionally
call disable_interrupts() where your v1 of this patch
calls devm_free_irq(). That would be a reasonable clean
solution I think.

Regards,

Hans




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