Messages in this thread Patch in this message | | | From | Reinette Chatre <> | Subject | [PATCH V2] x86/resctrl: Fix rdt_find_domain() return value and checks | Date | Mon, 10 Dec 2018 14:31:13 -0800 |
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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. By 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: d89b7379015f ("x86/intel_rdt/cqm: Add mon_data") Fixes: 521348b011d6 ("x86/intel_rdt: Introduce utility to obtain CDP peer") Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> --- V2: - Force error value to be -ENODEV when negative domain id provided - Rewrite commit message to describe why error value needs to be forced in addition to the original fix
arch/x86/kernel/cpu/resctrl/core.c | 2 +- arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 2 +- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c index 2ec252be4ed9..c3a9dc63edf2 100644 --- 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 index ba11f54f5ab8..3b943ace786c 100644 --- 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 index 017505017bdb..8388adf241b2 100644 --- 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; } -- 2.17.0
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