On Wed, Aug 21, 2019 at 2:10 PM Anju T Sudhakar <a...@linux.vnet.ibm.com> wrote:
>
> 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 lookup for an existing 'imc' directory,
> and do not invoke debugfs_create_dir(), if the debugfs interface for
> imc already exists.
>
> This patch is based on:
> https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-July/192979.html
>
> Signed-off-by: Anju T Sudhakar <a...@linux.vnet.ibm.com>
> Tested-by: Nageswara R Sastry <rnsas...@linux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/powernv/opal-imc.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c
> b/arch/powerpc/platforms/powernv/opal-imc.c
> index e04b20625cb9..fc2f0e60a44d 100644
> --- a/arch/powerpc/platforms/powernv/opal-imc.c
> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
> @@ -55,14 +55,19 @@ static void export_imc_mode_and_cmd(struct device_node
> *node,
> static u64 loc, *imc_mode_addr, *imc_cmd_addr;
> char mode[16], cmd[16];
> u32 cb_offset;
> + struct dentry *dir = NULL;
> struct imc_mem_info *ptr = pmu_ptr->mem_info;
>
> +
> + /* Return, if 'imc' interface already exists */
> + dir = debugfs_lookup("imc", powerpc_debugfs_root);
> + if (dir) {
> + dput(dir);
> + return;
> + }
> imc_debugfs_parent = debugfs_create_dir("imc", powerpc_debugfs_root);
Is there a reason why we create the debugfs directory here and not in
opal_imc_counters_probe()? There's logic to remove the debugfs
directory in _probe() already so it seems like a more natural place to
it.
>
> - /*
> - * Return here, either because 'imc' directory already exists,
> - * Or failed to create a new one.
> - */
> + /* Return here, if failed to create the directory */
> if (!imc_debugfs_parent)
> return;
>
> --
> 2.20.1
>
