Messages in this thread Patch in this message | | | From | "Fenghua Yu" <> | Subject | [PATCH 1/3] x86/intel_rdt: Fix kernfs_to_rdtgroup to know about "info/*" directories | Date | Fri, 11 Nov 2016 17:02:36 -0800 |
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From: Fenghua Yu <fenghua.yu@intel.com>
We saw a kernel oops on NULL pointer when we ran "rmdir info". This is because the "info" directory and per-resource subdirectories of "info" do not use "kn->priv" to point to a "struct rdtgroup".
Also change error code from -ENOENT to the more appropriate -EPERM so the user sees "Operation not permitted".
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> --- arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index 4795880..cff286e 100644 --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -644,16 +644,29 @@ static int parse_rdtgroupfs_options(char *data) */ static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn) { - if (kernfs_type(kn) == KERNFS_DIR) - return kn->priv; - else + if (kernfs_type(kn) == KERNFS_DIR) { + /* + * All the resource directories use "kn->priv" + * to point to the "struct rdtgroup" for the + * resource. "info" and its subdirectories don't + * have rdtgroup structures, so return NULL here. + */ + if (kn == kn_info || kn->parent == kn_info) + return NULL; + else + return kn->priv; + } else { return kn->parent->priv; + } } struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn) { struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn); + if (!rdtgrp) + return NULL; + atomic_inc(&rdtgrp->waitcount); kernfs_break_active_protection(kn); @@ -670,6 +683,9 @@ void rdtgroup_kn_unlock(struct kernfs_node *kn) { struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn); + if (!rdtgrp) + return; + mutex_unlock(&rdtgroup_mutex); if (atomic_dec_and_test(&rdtgrp->waitcount) && @@ -918,7 +934,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn) rdtgrp = rdtgroup_kn_lock_live(kn); if (!rdtgrp) { rdtgroup_kn_unlock(kn); - return -ENOENT; + return -EPERM; } /* Give any tasks back to the default group */ -- 2.5.0
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