tpm, tpm_tis: Avoid cache incoherency in test for interrupts

The interrupt handler that sets the boolean variable irq_tested may run on
another CPU as the thread that checks irq_tested as part of the irq test in
tpm_tis_send().

Since nothing guarantees cache coherency between CPUs for unsynchronized
accesses to boolean variables the testing thread might not perceive the
value change done in the interrupt handler.

Avoid this issue by setting the bit TPM_TIS_IRQ_TESTED in the flags field
of the tpm_tis_data struct and by accessing this field with the bit
manipulating functions that provide cache coherency.

Also convert all other existing sites to use the proper macros when
accessing this bitfield.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Tested-by: Michael Niewöhner <linux@mniewoehner.de>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index b68479e0de10..57718f43cf64 100644
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -87,13 +87,13 @@ enum tpm_tis_flags {
 	TPM_TIS_ITPM_WORKAROUND		= BIT(0),
 	TPM_TIS_INVALID_STATUS		= BIT(1),
 	TPM_TIS_DEFAULT_CANCELLATION	= BIT(2),
+	TPM_TIS_IRQ_TESTED		= BIT(3),
 };
 
 struct tpm_tis_data {
 	u16 manufacturer_id;
 	int locality;
 	int irq;
-	bool irq_tested;
 	unsigned long flags;
 	void __iomem *ilb_base_addr;
 	u16 clkrun_enabled;