6.6-stable review patch. If anyone has any objections, please let me know.
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From: Dave Jiang dave.jiang@intel.com
commit 36a1c2ee50f573972aea3c3019555f47ee0094c0 upstream.
The new helper "cxl_num_decoders_committed()" added a lockdep assertion to validate that port->commit_end is protected against modification. That assertion fires in init_hdm_decoder() where it is initializing port->commit_end. Given that it is both accessing and writing that property it obstensibly needs the lock.
In practice, CXL decoder commit rules (must commit in order) and the in-order discovery of device decoders makes the manipulation of ->commit_end in init_hdm_decoder() safe. However, rather than rely on the subtle rules of CXL hardware, just make the implementation obviously correct from a software perspective.
The Fixes: tag is only for cleaning up a lockdep splat, there is no functional issue addressed by this fix.
Fixes: 458ba8189cb4 ("cxl: Add cxl_decoders_committed() helper") Signed-off-by: Dave Jiang dave.jiang@intel.com Link: https://lore.kernel.org/r/170025232811.2147250.16376901801315194121.stgit@dj... Acked-by: Davidlohr Bueso dave@stgolabs.net Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cxl/core/hdm.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/cxl/core/hdm.c +++ b/drivers/cxl/core/hdm.c @@ -848,6 +848,8 @@ static int init_hdm_decoder(struct cxl_p cxld->target_type = CXL_DECODER_HOSTONLYMEM; else cxld->target_type = CXL_DECODER_DEVMEM; + + guard(rwsem_write)(&cxl_region_rwsem); if (cxld->id != cxl_num_decoders_committed(port)) { dev_warn(&port->dev, "decoder%d.%d: Committed out of order\n",