Re: [PATCH] platform/powernv: Avoid re-registration of imc debugfs directory
From: "Oliver O'Halloran" <oohall@gmail.com>
Date: 2019-08-21 04:48:54
On Wed, Aug 21, 2019 at 2:10 PM Anju T Sudhakar [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> Tested-by: Nageswara R Sastry <redacted> --- 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