Re: [PATCH 6/6] powerpc: powernv: no need to check return value of debugfs_create functions
"Oliver O'Halloran" writes:
> On Mon, Feb 10, 2020 at 12:12 AM Greg Kroah-Hartman
> wrote:
>>
>> When calling debugfs functions, there is no need to ever check the
>> return value. The function can work or not, but the code logic should
>> never do something different based on this.
>
> For memtrace debugfs is the only way to actually use the feature. It'd
> be nice if it still printed out *something* if it failed to create the
> files rather than just being mysteriously absent
That's true, but the current code doesn't actually do that anyway.
>> diff --git a/arch/powerpc/platforms/powernv/memtrace.c
>> b/arch/powerpc/platforms/powernv/memtrace.c
>> index eb2e75dac369..d6d64f8718e6 100644
>> --- a/arch/powerpc/platforms/powernv/memtrace.c
>> +++ b/arch/powerpc/platforms/powernv/memtrace.c
>> @@ -187,11 +187,6 @@ static int memtrace_init_debugfs(void)
>>
>> snprintf(ent->name, 16, "%08x", ent->nid);
>> dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
>> - if (!dir) {
>> - pr_err("Failed to create debugfs directory for node
>> %d\n",
>> - ent->nid);
>> - return -1;
>> - }
debugfs_create_dir() doesn't return NULL on error, it returns
ERR_PTR(-ENOMEM), which will not trigger that pr_err().
So I've merged this and if someone wants to they can send a follow-up to
do proper error checking in memtrace.c
cheers
Re: [PATCH 6/6] powerpc: powernv: no need to check return value of debugfs_create functions
On Tue, Feb 11, 2020 at 02:01:53AM +1100, Oliver O'Halloran wrote: > On Mon, Feb 10, 2020 at 12:12 AM Greg Kroah-Hartman > wrote: > > > > When calling debugfs functions, there is no need to ever check the > > return value. The function can work or not, but the code logic should > > never do something different based on this. > > For memtrace debugfs is the only way to actually use the feature. It'd > be nice if it still printed out *something* if it failed to create the > files rather than just being mysteriously absent, but maybe debugfs > itself does that. Looks fine otherwise. No, debugfs will only spit out an error message to the log if a file/directory is attempted to be created for an already present file/directory. For other failures, no error will be printed, other than the normal lower-level "out of memory" issues that might rarely happen. thanks, greg k-h
Re: [PATCH 6/6] powerpc: powernv: no need to check return value of debugfs_create functions
On Mon, Feb 10, 2020 at 12:12 AM Greg Kroah-Hartman
wrote:
>
> When calling debugfs functions, there is no need to ever check the
> return value. The function can work or not, but the code logic should
> never do something different based on this.
For memtrace debugfs is the only way to actually use the feature. It'd
be nice if it still printed out *something* if it failed to create the
files rather than just being mysteriously absent, but maybe debugfs
itself does that. Looks fine otherwise.
Reviewed-by: Oliver O'Halloran
> Cc: Benjamin Herrenschmidt
> Cc: Paul Mackerras
> Cc: Michael Ellerman
> Cc: Sukadev Bhattiprolu
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Greg Kroah-Hartman
> ---
> arch/powerpc/platforms/powernv/memtrace.c | 7
> arch/powerpc/platforms/powernv/opal-imc.c | 24 --
> arch/powerpc/platforms/powernv/pci-ioda.c | 5 ---
> arch/powerpc/platforms/powernv/vas-debug.c | 37 ++
> 4 files changed, 10 insertions(+), 63 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/memtrace.c
> b/arch/powerpc/platforms/powernv/memtrace.c
> index eb2e75dac369..d6d64f8718e6 100644
> --- a/arch/powerpc/platforms/powernv/memtrace.c
> +++ b/arch/powerpc/platforms/powernv/memtrace.c
> @@ -187,11 +187,6 @@ static int memtrace_init_debugfs(void)
>
> snprintf(ent->name, 16, "%08x", ent->nid);
> dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
> - if (!dir) {
> - pr_err("Failed to create debugfs directory for node
> %d\n",
> - ent->nid);
> - return -1;
> - }
>
> ent->dir = dir;
> debugfs_create_file("trace", 0400, dir, ent, _fops);
> @@ -314,8 +309,6 @@ static int memtrace_init(void)
> {
> memtrace_debugfs_dir = debugfs_create_dir("memtrace",
> powerpc_debugfs_root);
> - if (!memtrace_debugfs_dir)
> - return -1;
>
> debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
> NULL, _init_fops);
> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c
> b/arch/powerpc/platforms/powernv/opal-imc.c
> index 000b350d4060..968b9a4d1cd9 100644
> --- a/arch/powerpc/platforms/powernv/opal-imc.c
> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
> @@ -35,11 +35,10 @@ static int imc_mem_set(void *data, u64 val)
> }
> DEFINE_DEBUGFS_ATTRIBUTE(fops_imc_x64, imc_mem_get, imc_mem_set,
> "0x%016llx\n");
>
> -static struct dentry *imc_debugfs_create_x64(const char *name, umode_t mode,
> -struct dentry *parent, u64
> *value)
> +static void imc_debugfs_create_x64(const char *name, umode_t mode,
> + struct dentry *parent, u64 *value)
> {
> - return debugfs_create_file_unsafe(name, mode, parent,
> - value, _imc_x64);
> + debugfs_create_file_unsafe(name, mode, parent, value, _imc_x64);
> }
>
> /*
> @@ -59,9 +58,6 @@ static void export_imc_mode_and_cmd(struct device_node
> *node,
>
> imc_debugfs_parent = debugfs_create_dir("imc", powerpc_debugfs_root);
>
> - if (!imc_debugfs_parent)
> - return;
> -
> if (of_property_read_u32(node, "cb_offset", _offset))
> cb_offset = IMC_CNTL_BLK_OFFSET;
>
> @@ -69,21 +65,15 @@ static void export_imc_mode_and_cmd(struct device_node
> *node,
> loc = (u64)(ptr->vbase) + cb_offset;
> imc_mode_addr = (u64 *)(loc + IMC_CNTL_BLK_MODE_OFFSET);
> sprintf(mode, "imc_mode_%d", (u32)(ptr->id));
> - if (!imc_debugfs_create_x64(mode, 0600, imc_debugfs_parent,
> - imc_mode_addr))
> - goto err;
> + imc_debugfs_create_x64(mode, 0600, imc_debugfs_parent,
> + imc_mode_addr);
>
> imc_cmd_addr = (u64 *)(loc + IMC_CNTL_BLK_CMD_OFFSET);
> sprintf(cmd, "imc_cmd_%d", (u32)(ptr->id));
> - if (!imc_debugfs_create_x64(cmd, 0600, imc_debugfs_parent,
> - imc_cmd_addr))
> - goto err;
> + imc_debugfs_create_x64(cmd, 0600, imc_debugfs_parent,
> + imc_cmd_addr);
> ptr++;
> }
> - return;
> -
> -err:
> - debugfs_remove_recursive(imc_debugfs_parent);
> }
>
> /*
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c
> b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 22c22cd7bd82..57d3a6af1d52 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -3174,11 +3174,6 @@ static void pnv_pci_ioda_create_dbgfs(void)
>
> sprintf(name, "PCI%04x",
[PATCH 6/6] powerpc: powernv: no need to check return value of debugfs_create functions
When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Michael Ellerman
Cc: Sukadev Bhattiprolu
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Greg Kroah-Hartman
---
arch/powerpc/platforms/powernv/memtrace.c | 7
arch/powerpc/platforms/powernv/opal-imc.c | 24 --
arch/powerpc/platforms/powernv/pci-ioda.c | 5 ---
arch/powerpc/platforms/powernv/vas-debug.c | 37 ++
4 files changed, 10 insertions(+), 63 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/memtrace.c
b/arch/powerpc/platforms/powernv/memtrace.c
index eb2e75dac369..d6d64f8718e6 100644
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -187,11 +187,6 @@ static int memtrace_init_debugfs(void)
snprintf(ent->name, 16, "%08x", ent->nid);
dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
- if (!dir) {
- pr_err("Failed to create debugfs directory for node
%d\n",
- ent->nid);
- return -1;
- }
ent->dir = dir;
debugfs_create_file("trace", 0400, dir, ent, _fops);
@@ -314,8 +309,6 @@ static int memtrace_init(void)
{
memtrace_debugfs_dir = debugfs_create_dir("memtrace",
powerpc_debugfs_root);
- if (!memtrace_debugfs_dir)
- return -1;
debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
NULL, _init_fops);
diff --git a/arch/powerpc/platforms/powernv/opal-imc.c
b/arch/powerpc/platforms/powernv/opal-imc.c
index 000b350d4060..968b9a4d1cd9 100644
--- a/arch/powerpc/platforms/powernv/opal-imc.c
+++ b/arch/powerpc/platforms/powernv/opal-imc.c
@@ -35,11 +35,10 @@ static int imc_mem_set(void *data, u64 val)
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_imc_x64, imc_mem_get, imc_mem_set,
"0x%016llx\n");
-static struct dentry *imc_debugfs_create_x64(const char *name, umode_t mode,
-struct dentry *parent, u64 *value)
+static void imc_debugfs_create_x64(const char *name, umode_t mode,
+ struct dentry *parent, u64 *value)
{
- return debugfs_create_file_unsafe(name, mode, parent,
- value, _imc_x64);
+ debugfs_create_file_unsafe(name, mode, parent, value, _imc_x64);
}
/*
@@ -59,9 +58,6 @@ static void export_imc_mode_and_cmd(struct device_node *node,
imc_debugfs_parent = debugfs_create_dir("imc", powerpc_debugfs_root);
- if (!imc_debugfs_parent)
- return;
-
if (of_property_read_u32(node, "cb_offset", _offset))
cb_offset = IMC_CNTL_BLK_OFFSET;
@@ -69,21 +65,15 @@ static void export_imc_mode_and_cmd(struct device_node
*node,
loc = (u64)(ptr->vbase) + cb_offset;
imc_mode_addr = (u64 *)(loc + IMC_CNTL_BLK_MODE_OFFSET);
sprintf(mode, "imc_mode_%d", (u32)(ptr->id));
- if (!imc_debugfs_create_x64(mode, 0600, imc_debugfs_parent,
- imc_mode_addr))
- goto err;
+ imc_debugfs_create_x64(mode, 0600, imc_debugfs_parent,
+ imc_mode_addr);
imc_cmd_addr = (u64 *)(loc + IMC_CNTL_BLK_CMD_OFFSET);
sprintf(cmd, "imc_cmd_%d", (u32)(ptr->id));
- if (!imc_debugfs_create_x64(cmd, 0600, imc_debugfs_parent,
- imc_cmd_addr))
- goto err;
+ imc_debugfs_create_x64(cmd, 0600, imc_debugfs_parent,
+ imc_cmd_addr);
ptr++;
}
- return;
-
-err:
- debugfs_remove_recursive(imc_debugfs_parent);
}
/*
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c
b/arch/powerpc/platforms/powernv/pci-ioda.c
index 22c22cd7bd82..57d3a6af1d52 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -3174,11 +3174,6 @@ static void pnv_pci_ioda_create_dbgfs(void)
sprintf(name, "PCI%04x", hose->global_number);
phb->dbgfs = debugfs_create_dir(name, powerpc_debugfs_root);
- if (!phb->dbgfs) {
- pr_warn("%s: Error on creating debugfs on PHB#%x\n",
- __func__, hose->global_number);
- continue;
- }
debugfs_create_file_unsafe("dump_diag_regs", 0200, phb->dbgfs,
phb, _pci_diag_data_fops);
diff --git a/arch/powerpc/platforms/powernv/vas-debug.c
