x86/intel_rdt: Provide pseudo-locking hooks within rdt_mount

Stephen Rothwell reported that the Cache Pseudo-Locking enabling and the
kernfs support for mounting with fs_context are conflicting.

In preparation for a conflict-free merge between the two repos some no-op
hooks are created within the RDT mount function being changed by the two
features. The goal is for this commit to be placed on a minimal no-rebase
branch to be consumed by both features.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: vikas.shivappa@linux.intel.com
Cc: gavin.hindman@intel.com
Cc: jithu.joseph@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Cc: David Howells <dhowells@redhat.com>
Link: https://lkml.kernel.org/r/410697ead08978bd12111c0afc4ce9e7bd71a5fe.1529706536.git.reinette.chatre@intel.com

diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index 39752825e3760cbcff2c09efc0963e621076653a..be152b3b25432995514597ecaa505d6cc90153ba 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -468,4 +468,13 @@ void cqm_handle_limbo(struct work_struct *work);
 bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d);
 void __check_limbo(struct rdt_domain *d, bool force_free);
 
+/*
+ * Define the hooks for Cache Pseudo-Locking to use within rdt_mount().
+ * These are no-ops provided for the new kernfs changes to use as a
+ * baseline in preparation for a conflict-free merge between it
+ * (kernfs changes) and the Cache Pseudo-Locking enabling.
+ */
+static inline int rdt_pseudo_lock_init(void) { return 0; }
+static inline void rdt_pseudo_lock_release(void) { }
+
 #endif /* _ASM_X86_INTEL_RDT_H */

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 749856a2e736738feab416e3980054e5b5a699b3..fa668f9670625975ca4de28e973f87f742ad74f1 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1289,10 +1289,16 @@ static struct dentry *rdt_mount(struct file_system_type *fs_type,
                rdtgroup_default.mon.mon_data_kn = kn_mondata;
        }
 
+       ret = rdt_pseudo_lock_init();
+       if (ret) {
+               dentry = ERR_PTR(ret);
+               goto out_mondata;
+       }
+
        dentry = kernfs_mount(fs_type, flags, rdt_root,
                              RDTGROUP_SUPER_MAGIC, NULL);
        if (IS_ERR(dentry))
-               goto out_mondata;
+               goto out_psl;
 
        if (rdt_alloc_capable)
                static_branch_enable_cpuslocked(&rdt_alloc_enable_key);
@@ -1310,6 +1316,8 @@ static struct dentry *rdt_mount(struct file_system_type *fs_type,
 
        goto out;
 
+out_psl:
+       rdt_pseudo_lock_release();
 out_mondata:
        if (rdt_mon_capable)
                kernfs_remove(kn_mondata);