On Thu, Sep 10, 2026 at 10:44:31AM +0800, Richard Lyu wrote: > The comment above the wmb() in tpm_pm_resume() states that the barrier > guarantees TPM_CHIP_FLAG_SUSPENDED is written last, so that hwrng does > not activate before the chip has been fully resumed. It cannot do so: > it is placed after the store that clears the flag, and therefore does > not order the preceding resume work before that store. It also has > nothing to pair with, as tpm_try_get_ops() contains no matching read > barrier. > > Drop the barrier along with the comment rather than leave a no-op > behind. Should such ordering turn out to be needed, it would require > paired barriers or locking. > > Link: > https://lore.kernel.org/all/[email protected]/ > Signed-off-by: Richard Lyu <[email protected]> > > --- > v2: > - Drop the Fixes tag: this is a cleanup, not a bug fix. > - Link to v1: https://lore.kernel.org/all/aqIVn0cDBvIYKggE@r1chard/ > --- > drivers/char/tpm/tpm-interface.c | 6 ------ > 1 file changed, 6 deletions(-) > > diff --git a/drivers/char/tpm/tpm-interface.c > b/drivers/char/tpm/tpm-interface.c > index b4e749e70b02..0bab78c8767c 100644 > --- a/drivers/char/tpm/tpm-interface.c > +++ b/drivers/char/tpm/tpm-interface.c > @@ -497,12 +497,6 @@ int tpm_pm_resume(struct device *dev) > > chip->flags &= ~TPM_CHIP_FLAG_SUSPENDED; > > - /* > - * Guarantee that SUSPENDED is written last, so that hwrng does not > - * activate before the chip has been fully resumed. > - */ > - wmb(); > - > return 0; > } > EXPORT_SYMBOL_GPL(tpm_pm_resume); > -- > 2.51.0 >
Reviewed-by: Jarkko Sakkinen <[email protected]> BR, Jarkko
