tpm: Allow system suspend to continue when TPM suspend fails

Linux Kernel / Linux Kernel - Jason A. Donenfeld [zx2c4.com] - 6 January 2023 22:25 UTC

TPM 1 is sometimes broken across system suspends, due to races or locking issues or something else that haven't been diagnosed or fixed yet, most likely having to do with concurrent reads from the TPM's hardware random number generator driver. These issues prevent the system from actually suspending, with errors like:

tpm tpm0: A TPM error (28) occurred continue selftest

tpm tpm0: A TPM error (28) occurred attempting get random

tpm tpm0: Error (28) sending savestate before suspend tpm_tis 00:08: PM: __pnp_bus_suspend(): tpm_pm_suspend+0x0/0x80 returns 28 tpm_tis 00:08: PM: dpm_run_callback(): pnp_bus_suspend+0x0/0x10 returns 28 tpm_tis 00:08: PM: failed to suspend: error 28 PM: Some devices failed to suspend, or early wake event detected

This issue was partially fixed by 23393c646142 ("char: tpm: Protect tpm_pm_suspend with locks"), in a last minute 6.1 commit that Linus took directly because the TPM maintainers weren't available. However, it seems like this just addresses the most common cases of the bug, rather than addressing it entirely. So there are more things to fix still, apparently.

In lieu of actually fixing the underlying bug, just allow system suspend to continue, so that laptops still go to sleep fine. Later, this can be reverted when the real bug is fixed.

Link: https://lore.kernel.org/lkml/7cbe96cf-e0b5-ba63-d1b4-f63d2e826efa@suse.cz/ Cc: stable@vger.kernel.org # 6.1+

1382999aa054 tpm: Allow system suspend to continue when TPM suspend fails
drivers/char/tpm/tpm-interface.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

Upstream: git.kernel.org


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