From: Dave Jiang Date: Fri, 17 Nov 2023 20:18:48 +0000 (-0700) Subject: cxl/hdm: Fix a benign lockdep splat X-Git-Tag: v6.6.17~1522 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0a460481df435f955d569b44e7674ff81dfc7f74;p=platform%2Fkernel%2Flinux-rpi.git cxl/hdm: Fix a benign lockdep splat 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 Link: https://lore.kernel.org/r/170025232811.2147250.16376901801315194121.stgit@djiang5-mobl3 Acked-by: Davidlohr Bueso Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c index 54a535f..9066465 100644 --- a/drivers/cxl/core/hdm.c +++ b/drivers/cxl/core/hdm.c @@ -848,6 +848,8 @@ 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",