Re: [PATCH 5.10 002/299] bus: mhi: core: Clear configuration from channel context during reset
From: Pavel Machek <hidden>
Date: 2021-05-10 20:56:55
Also in:
lkml
Hi!
From: Bhaumik Bhatt <redacted> commit 47705c08465931923e2f2b506986ca0bdf80380d upstream. When clearing up the channel context after client drivers are done using channels, the configuration is currently not being reset entirely. Ensure this is done to appropriately handle issues where clients unaware of the context state end up calling functions which expect a context.
quoted hunk ↗ jump to hunk
+++ b/drivers/bus/mhi/core/init.c@@ -544,6 +544,7 @@ void mhi_deinit_chan_ctxt(struct mhi_con + u32 tmp;@@ -554,7 +555,19 @@ void mhi_deinit_chan_ctxt(struct mhi_con
...
+ tmp = chan_ctxt->chcfg; + tmp &= ~CHAN_CTX_CHSTATE_MASK; + tmp |= (MHI_CH_STATE_DISABLED << CHAN_CTX_CHSTATE_SHIFT); + chan_ctxt->chcfg = tmp; + + /* Update to all cores */ + smp_wmb(); }
This is really interesting code; author was careful to make sure chcfg is updated atomically, but C compiler is free to undo that. Plus, this will make all kinds of checkers angry. Does the file need to use READ_ONCE and WRITE_ONCE? Best regards, Pavel -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Attachments
- signature.asc [application/pgp-signature] 181 bytes