From 36a1c2ee50f573972aea3c3019555f47ee0094c0 Mon Sep 17 00:00:00 2001 From: Dave Jiang Date: Fri, 17 Nov 2023 13:18:48 -0700 Subject: cxl/hdm: Fix a benign lockdep splat 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 Link: https://lore.kernel.org/r/170025232811.2147250.16376901801315194121.stgit@djiang5-mobl3 Acked-by: Davidlohr Bueso Signed-off-by: Dan Williams --- drivers/cxl/core/hdm.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/cxl/core/hdm.c') diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c index 1cc9be85ba4c..529baa8a1759 100644 --- a/drivers/cxl/core/hdm.c +++ b/drivers/cxl/core/hdm.c @@ -839,6 +839,8 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld, 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", -- cgit v1.2.3