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tpm, tpm_tis: Avoid cache incoherency in test for interrupts
authorLino Sanfilippo <l.sanfilippo@kunbus.com>
Thu, 24 Nov 2022 13:55:25 +0000 (14:55 +0100)
committerJarkko Sakkinen <jarkko@kernel.org>
Mon, 24 Apr 2023 13:15:53 +0000 (16:15 +0300)
commit858e8b792d06f45c427897bd90205a1d90bf430f
tree6ea73650a4d7bf67f75d45a931bcaa9098addb36
parent099f26f22f5834ad744aee093ed4d11de13cac15
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>
drivers/char/tpm/tpm_tis.c
drivers/char/tpm/tpm_tis_core.c
drivers/char/tpm/tpm_tis_core.h