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cxl/region: Fix region reference target accounting

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Dan reports:

    The error handling in cxl_port_attach_region() looks like it might
    have a similar bug.  The cxl_rr->nr_targets++; might want a --.

    That function is more complicated.

Indeed cxl_rr->nr_targets leaks when cxl_rr_ep_add() fails, but that
flow is not clear. Fix the bug and the clarity by separating the 'new'
region-reference case from the 'extend' region-reference case. This also
moves the host-physical-address (HPA) validation, that the HPA of a new
region being accounted to the port is greater than the HPA of all other
regions associated with the port, to alloc_region_ref().

Introduce @nr_targets_inc to track when the error exit path needs to
clean up cxl_rr->nr_targets.

Fixes: 384e624bb2 ("cxl/region: Attach endpoint decoders")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: http://lore.kernel.org/r/165939482134.252363.1915691883146696327.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2022-08-01 12:55:30 -07:00
parent 69c9961387
commit e29a8995d6
1 changed files with 43 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
drivers/cxl/core/region.c
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@ -648,12 +648,26 @@ static struct cxl_decoder *cxl_region_find_decoder(struct cxl_port *port,
static struct cxl_region_ref *alloc_region_ref(struct cxl_port *port,
struct cxl_region *cxlr)
{
struct cxl_region_ref *cxl_rr;
struct cxl_region_params *p = &cxlr->params;
struct cxl_region_ref *cxl_rr, *iter;
unsigned long index;
int rc;
xa_for_each(&port->regions, index, iter) {
struct cxl_region_params *ip = &iter->region->params;
if (ip->res->start > p->res->start) {
dev_dbg(&cxlr->dev,
"%s: HPA order violation %s:%pr vs %pr\n",
dev_name(&port->dev),
dev_name(&iter->region->dev), ip->res, p->res);
return ERR_PTR(-EBUSY);
}
}
cxl_rr = kzalloc(sizeof(*cxl_rr), GFP_KERNEL);
if (!cxl_rr)
return NULL;
return ERR_PTR(-ENOMEM);
cxl_rr->port = port;
cxl_rr->region = cxlr;
cxl_rr->nr_targets = 1;
@ -665,7 +679,7 @@ static struct cxl_region_ref *alloc_region_ref(struct cxl_port *port,
"%s: failed to track region reference: %d\n",
dev_name(&port->dev), rc);
kfree(cxl_rr);
return NULL;
return ERR_PTR(rc);
}
return cxl_rr;
@ -740,33 +754,25 @@ static int cxl_port_attach_region(struct cxl_port *port,
{
struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
struct cxl_ep *ep = cxl_ep_load(port, cxlmd);
struct cxl_region_ref *cxl_rr = NULL, *iter;
struct cxl_region_params *p = &cxlr->params;
struct cxl_decoder *cxld = NULL;
struct cxl_region_ref *cxl_rr;
bool nr_targets_inc = false;
struct cxl_decoder *cxld;
unsigned long index;
int rc = -EBUSY;
lockdep_assert_held_write(&cxl_region_rwsem);
xa_for_each(&port->regions, index, iter) {
struct cxl_region_params *ip = &iter->region->params;
if (iter->region == cxlr)
cxl_rr = iter;
if (ip->res->start > p->res->start) {
dev_dbg(&cxlr->dev,
"%s: HPA order violation %s:%pr vs %pr\n",
dev_name(&port->dev),
dev_name(&iter->region->dev), ip->res, p->res);
return -EBUSY;
}
}
cxl_rr = cxl_rr_load(port, cxlr);
if (cxl_rr) {
struct cxl_ep *ep_iter;
int found = 0;
cxld = cxl_rr->decoder;
/*
* Walk the existing endpoints that have been attached to
* @cxlr at @port and see if they share the same 'next' port
* in the downstream direction. I.e. endpoints that share common
* upstream switch.
*/
xa_for_each(&cxl_rr->endpoints, index, ep_iter) {
if (ep_iter == ep)
continue;
@ -777,22 +783,29 @@ static int cxl_port_attach_region(struct cxl_port *port,
}
/*
* If this is a new target or if this port is direct connected
* to this endpoint then add to the target count.
* New target port, or @port is an endpoint port that always
* accounts its own local decode as a target.
*/
if (!found || !ep->next)
if (!found || !ep->next) {
cxl_rr->nr_targets++;
nr_targets_inc = true;
}
/*
* The decoder for @cxlr was allocated when the region was first
* attached to @port.
*/
cxld = cxl_rr->decoder;
} else {
cxl_rr = alloc_region_ref(port, cxlr);
if (!cxl_rr) {
if (IS_ERR(cxl_rr)) {
dev_dbg(&cxlr->dev,
"%s: failed to allocate region reference\n",
dev_name(&port->dev));
return -ENOMEM;
return PTR_ERR(cxl_rr);
}
}
nr_targets_inc = true;
if (!cxld) {
if (port == cxled_to_port(cxled))
cxld = &cxled->cxld;
else
@ -835,6 +848,8 @@ static int cxl_port_attach_region(struct cxl_port *port,
return 0;
out_erase:
if (nr_targets_inc)
cxl_rr->nr_targets--;
if (cxl_rr->nr_eps == 0)
free_region_ref(cxl_rr);
return rc;