linux-kernel - Re: [PATCH] cxl/region: Fix memregion leaks in devm_cxl_add

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Message-ID: <66350bb1d3817_1aefb294ba@dwillia2-mobl3.amr.corp.intel.com.notmuch>
Date: Fri, 3 May 2024 09:07:13 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: "Zhijian Li (Fujitsu)" <lizhijian@...itsu.com>, Ira Weiny
	<ira.weiny@...el.com>, "dave@...olabs.net" <dave@...olabs.net>,
	"jonathan.cameron@...wei.com" <Jonathan.Cameron@...wei.com>,
	"dave.jiang@...el.com" <dave.jiang@...el.com>, "alison.schofield@...el.com"
	<alison.schofield@...el.com>, "vishal.l.verma@...el.com"
	<vishal.l.verma@...el.com>, "dan.j.williams@...el.com"
	<dan.j.williams@...el.com>, "linux-cxl@...r.kernel.org"
	<linux-cxl@...r.kernel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cxl/region: Fix memregion leaks in devm_cxl_add_region()

Zhijian Li (Fujitsu) wrote:
> > I'm not following what the problem is you are trying to fix.  This seems
> > like it just moves the memregion_free() around a bit but the logic is the
> > same.
> 
> This patch not only memregion_free(id) out of cxl_region_alloc() but
> also add an  extra memregion_free(id) in EINVAL case which led to a
> memory leak previously
> 

I think I would prefer to just eliminate that failure case, something
like:

-- >8 --
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 5c186e0a39b9..95ba32f8649c 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2352,15 +2352,6 @@ static struct cxl_region *devm_cxl_add_region(struct cxl_root_decoder *cxlrd,
        struct device *dev;
        int rc;
 
-       switch (mode) {
-       case CXL_DECODER_RAM:
-       case CXL_DECODER_PMEM:
-               break;
-       default:
-               dev_err(&cxlrd->cxlsd.cxld.dev, "unsupported mode %d\n", mode);
-               return ERR_PTR(-EINVAL);
-       }
-
        cxlr = cxl_region_alloc(cxlrd, id);
        if (IS_ERR(cxlr))
                return cxlr;
@@ -2415,6 +2406,15 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
 {
        int rc;
 
+       switch (mode) {
+       case CXL_DECODER_RAM:
+       case CXL_DECODER_PMEM:
+               break;
+       default:
+               dev_err(&cxlrd->cxlsd.cxld.dev, "unsupported mode %d\n", mode);
+               return ERR_PTR(-EINVAL);
+       }
+
        rc = memregion_alloc(GFP_KERNEL);
        if (rc < 0)
                return ERR_PTR(rc);