x86/resctrl: Fix rdt_find_domain() return value and checks

rchatre · suryasaimadhu · commit 52eb74339a62 · 2018-12-11T22:09:28.000+01:00
rdt_find_domain() returns an ERR_PTR() that is generated from a provided domain id when the value is negative. Care needs to be taken when creating an ERR_PTR() from this value because a subsequent check using IS_ERR() expects the error to be within the MAX_ERRNO range. Using an invalid domain id as an ERR_PTR() does work at this time since this is currently always -1. Using this undocumented assumption is fragile since future users of rdt_find_domain() may not be aware of thus assumption. Two related issues are addressed: - Ensure that rdt_find_domain() always returns a valid error value by forcing the error to be -ENODEV when a negative domain id is provided. - In a few instances the return value of rdt_find_domain() is just checked for NULL - fix these to include a check of ERR_PTR. Fixes: d89b737 ("x86/intel_rdt/cqm: Add mon_data") Fixes: 521348b ("x86/intel_rdt: Introduce utility to obtain CDP peer") Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: fenghua.yu@intel.com Cc: gavin.hindman@intel.com Cc: jithu.joseph@intel.com Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/b88cd4ff6a75995bf8db9b0ea546908fe50f69f3.1544479852.git.reinette.chatre@intel.com
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
@@ -454,7 +454,7 @@ struct rdt_domain *rdt_find_domain(struct rdt_resource *r, int id,
 	struct list_head *l;
 
 	if (id < 0)
-		return ERR_PTR(id);
+		return ERR_PTR(-ENODEV);
 
 	list_for_each(l, &r->domains) {
 		d = list_entry(l, struct rdt_domain, list);
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -534,7 +534,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
 
 	r = &rdt_resources_all[resid];
 	d = rdt_find_domain(r, domid, NULL);
-	if (!d) {
+	if (IS_ERR_OR_NULL(d)) {
 		ret = -ENOENT;
 		goto out;
 	}
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1029,7 +1029,7 @@ static int rdt_cdp_peer_get(struct rdt_resource *r, struct rdt_domain *d,
 	 * peer RDT CDP resource. Hence the WARN.
 	 */
 	_d_cdp = rdt_find_domain(_r_cdp, d->id, NULL);
-	if (WARN_ON(!_d_cdp)) {
+	if (WARN_ON(IS_ERR_OR_NULL(_d_cdp))) {
 		_r_cdp = NULL;
 		ret = -EINVAL;
 	}

Original file line number	Diff line number	Diff line change
`@@ -534,7 +534,7 @@ int rdtgroup_mondata_show(struct seq_file m, void arg)`
`534`	`534`
`535`	`535`	`r = &rdt_resources_all[resid];`
`536`	`536`	`d = rdt_find_domain(r, domid, NULL);`
`537`		`- if (!d) {`
	`537`	`+ if (IS_ERR_OR_NULL(d)) {`
`538`	`538`	`ret = -ENOENT;`
`539`	`539`	`goto out;`
`540`	`540`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1029,7 +1029,7 @@ static int rdt_cdp_peer_get(struct rdt_resource r, struct rdt_domain d,`
`1029`	`1029`	`* peer RDT CDP resource. Hence the WARN.`
`1030`	`1030`	`*/`
`1031`	`1031`	`_d_cdp = rdt_find_domain(_r_cdp, d->id, NULL);`
`1032`		`- if (WARN_ON(!_d_cdp)) {`
	`1032`	`+ if (WARN_ON(IS_ERR_OR_NULL(_d_cdp))) {`
`1033`	`1033`	`_r_cdp = NULL;`
`1034`	`1034`	`ret = -EINVAL;`
`1035`	`1035`	`}`