powerpc/powernv: Avoid re-registration of imc debugfs directory

export_imc_mode_and_cmd() function which creates the debugfs interface
for imc-mode and imc-command, is invoked when each nest pmu units is
registered.

When the first nest pmu unit is registered, export_imc_mode_and_cmd()
creates 'imc' directory under `/debug/powerpc/`. In the subsequent
invocations debugfs_create_dir() function returns, since the directory
already exists.

The recent commit <c33d442328f55> (debugfs: make error message a bit
more verbose), throws a warning if we try to invoke
`debugfs_create_dir()` with an already existing directory name.

Address this warning by making the debugfs directory registration in
the opal_imc_counters_probe() function, i.e invoke
export_imc_mode_and_cmd() function from the probe function.

Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Tested-by: Nageswara R Sastry <nasastry@in.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191127072035.4283-1-anju@linux.vnet.ibm.com

diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c
index e04b206..3b4518f 100644 (file)
--- a/arch/powerpc/platforms/powernv/opal-imc.c
+++ b/arch/powerpc/platforms/powernv/opal-imc.c
@@ -59,10 +59,6 @@ static void export_imc_mode_and_cmd(struct device_node *node,
 
        imc_debugfs_parent = debugfs_create_dir("imc", powerpc_debugfs_root);
 
-       /*
-        * Return here, either because 'imc' directory already exists,
-        * Or failed to create a new one.
-        */
        if (!imc_debugfs_parent)
                return;
 
@@ -135,7 +131,6 @@ static int imc_get_mem_addr_nest(struct device_node *node,
        }
 
        pmu_ptr->imc_counter_mmaped = true;
-       export_imc_mode_and_cmd(node, pmu_ptr);
        kfree(base_addr_arr);
        kfree(chipid_arr);
        return 0;
@@ -151,7 +146,7 @@ error:
  *                 and domain as the inputs.
  * Allocates memory for the struct imc_pmu, sets up its domain, size and offsets
  */
-static int imc_pmu_create(struct device_node *parent, int pmu_index, int domain)
+static struct imc_pmu *imc_pmu_create(struct device_node *parent, int pmu_index, int domain)
 {
        int ret = 0;
        struct imc_pmu *pmu_ptr;
@@ -159,27 +154,23 @@ static int imc_pmu_create(struct device_node *parent, int pmu_index, int domain)
 
        /* Return for unknown domain */
        if (domain < 0)
-               return -EINVAL;
+               return NULL;
 
        /* memory for pmu */
        pmu_ptr = kzalloc(sizeof(*pmu_ptr), GFP_KERNEL);
        if (!pmu_ptr)
-               return -ENOMEM;
+               return NULL;
 
        /* Set the domain */
        pmu_ptr->domain = domain;
 
        ret = of_property_read_u32(parent, "size", &pmu_ptr->counter_mem_size);
-       if (ret) {
-               ret = -EINVAL;
+       if (ret)
                goto free_pmu;
-       }
 
        if (!of_property_read_u32(parent, "offset", &offset)) {
-               if (imc_get_mem_addr_nest(parent, pmu_ptr, offset)) {
-                       ret = -EINVAL;
+               if (imc_get_mem_addr_nest(parent, pmu_ptr, offset))
                        goto free_pmu;
-               }
        }
 
        /* Function to register IMC pmu */
@@ -190,14 +181,14 @@ static int imc_pmu_create(struct device_node *parent, int pmu_index, int domain)
                if (pmu_ptr->domain == IMC_DOMAIN_NEST)
                        kfree(pmu_ptr->mem_info);
                kfree(pmu_ptr);
-               return ret;
+               return NULL;
        }
 
-       return 0;
+       return pmu_ptr;
 
 free_pmu:
        kfree(pmu_ptr);
-       return ret;
+       return NULL;
 }
 
 static void disable_nest_pmu_counters(void)
@@ -254,6 +245,7 @@ int get_max_nest_dev(void)
 static int opal_imc_counters_probe(struct platform_device *pdev)
 {
        struct device_node *imc_dev = pdev->dev.of_node;
+       struct imc_pmu *pmu;
        int pmu_count = 0, domain;
        bool core_imc_reg = false, thread_imc_reg = false;
        u32 type;
@@ -269,6 +261,7 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
        }
 
        for_each_compatible_node(imc_dev, NULL, IMC_DTB_UNIT_COMPAT) {
+               pmu = NULL;
                if (of_property_read_u32(imc_dev, "type", &type)) {
                        pr_warn("IMC Device without type property\n");
                        continue;
@@ -293,9 +286,13 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
                        break;
                }
 
-               if (!imc_pmu_create(imc_dev, pmu_count, domain)) {
-                       if (domain == IMC_DOMAIN_NEST)
+               pmu = imc_pmu_create(imc_dev, pmu_count, domain);
+               if (pmu != NULL) {
+                       if (domain == IMC_DOMAIN_NEST) {
+                               if (!imc_debugfs_parent)
+                                       export_imc_mode_and_cmd(imc_dev, pmu);
                                pmu_count++;
+                       }
                        if (domain == IMC_DOMAIN_CORE)
                                core_imc_reg = true;
                        if (domain == IMC_DOMAIN_THREAD)
@@ -303,10 +300,6 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
                }
        }
 
-       /* If none of the nest units are registered, remove debugfs interface */
-       if (pmu_count == 0)
-               debugfs_remove_recursive(imc_debugfs_parent);
-
        /* If core imc is not registered, unregister thread-imc */
        if (!core_imc_reg && thread_imc_reg)
                unregister_thread_imc();