From: Michael Ellerman <mpe@ellerman.id.au>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Paul Mackerras <paulus@ozlabs.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
kvm-ppc@vger.kernel.org
Subject: Re: [PATCH 2/6] powerpc: kvm: no need to check return value of debugfs_create functions
Date: Tue, 03 Mar 2020 18:46:23 +1100 [thread overview]
Message-ID: <87imjlswxc.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200209105901.1620958-2-gregkh@linuxfoundation.org>
Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:
> 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.
Except it does need to do something different, if the file was created
it needs to be removed in the remove path.
> diff --git a/arch/powerpc/kvm/timing.c b/arch/powerpc/kvm/timing.c
> index bfe4f106cffc..8e4791c6f2af 100644
> --- a/arch/powerpc/kvm/timing.c
> +++ b/arch/powerpc/kvm/timing.c
> @@ -207,19 +207,12 @@ static const struct file_operations kvmppc_exit_timing_fops = {
> void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu, unsigned int id)
> {
> static char dbg_fname[50];
> - struct dentry *debugfs_file;
>
> snprintf(dbg_fname, sizeof(dbg_fname), "vm%u_vcpu%u_timing",
> current->pid, id);
> - debugfs_file = debugfs_create_file(dbg_fname, 0666,
> - kvm_debugfs_dir, vcpu,
> - &kvmppc_exit_timing_fops);
> -
> - if (!debugfs_file) {
> - printk(KERN_ERR"%s: error creating debugfs file %s\n",
> - __func__, dbg_fname);
> - return;
> - }
> + debugfs_create_file(dbg_fname, 0666, kvm_debugfs_dir, vcpu,
> + &kvmppc_exit_timing_fops);
> +
>
> vcpu->arch.debugfs_exit_timing = debugfs_file;
> }
This doesn't build:
arch/powerpc/kvm/timing.c:217:35: error: 'debugfs_file' undeclared (first use in this function); did you mean 'debugfs_file_put'?
We can't just drop the assignment, we need the dentry to do the removal:
void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu)
{
if (vcpu->arch.debugfs_exit_timing) {
debugfs_remove(vcpu->arch.debugfs_exit_timing);
vcpu->arch.debugfs_exit_timing = NULL;
}
}
I squashed this in, which seems to work:
diff --git a/arch/powerpc/kvm/timing.c b/arch/powerpc/kvm/timing.c
index 8e4791c6f2af..5b7a66f86bd5 100644
--- a/arch/powerpc/kvm/timing.c
+++ b/arch/powerpc/kvm/timing.c
@@ -207,19 +207,19 @@ static const struct file_operations kvmppc_exit_timing_fops = {
void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu, unsigned int id)
{
static char dbg_fname[50];
+ struct dentry *debugfs_file;
snprintf(dbg_fname, sizeof(dbg_fname), "vm%u_vcpu%u_timing",
current->pid, id);
- debugfs_create_file(dbg_fname, 0666, kvm_debugfs_dir, vcpu,
- &kvmppc_exit_timing_fops);
-
+ debugfs_file = debugfs_create_file(dbg_fname, 0666, kvm_debugfs_dir,
+ vcpu, &kvmppc_exit_timing_fops);
vcpu->arch.debugfs_exit_timing = debugfs_file;
}
void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu)
{
- if (vcpu->arch.debugfs_exit_timing) {
+ if (!IS_ERR_OR_NULL(vcpu->arch.debugfs_exit_timing)) {
debugfs_remove(vcpu->arch.debugfs_exit_timing);
vcpu->arch.debugfs_exit_timing = NULL;
}
cheers
next prev parent reply other threads:[~2020-03-03 7:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-09 10:58 [PATCH 1/6] powerpc: kernel: no need to check return value of debugfs_create functions Greg Kroah-Hartman
2020-02-09 10:58 ` [PATCH 2/6] powerpc: kvm: " Greg Kroah-Hartman
2020-03-03 7:46 ` Michael Ellerman [this message]
2020-03-03 8:50 ` Greg Kroah-Hartman
2020-03-03 9:45 ` Michael Ellerman
2020-03-03 9:58 ` Greg Kroah-Hartman
2020-03-03 10:32 ` Michael Ellerman
2020-02-09 10:58 ` [PATCH 3/6] powerpc: mm: book3s64: hash_utils: " Greg Kroah-Hartman
2020-02-09 10:58 ` [PATCH 4/6] powerpc: mm: ptdump: " Greg Kroah-Hartman
2020-02-09 10:59 ` [PATCH 5/6] powerpc: cell: axon_msi: " Greg Kroah-Hartman
2020-02-09 10:59 ` [PATCH 6/6] powerpc: powernv: " Greg Kroah-Hartman
2020-02-10 15:01 ` Oliver O'Halloran
2020-02-10 15:19 ` Greg Kroah-Hartman
2020-03-03 9:52 ` Michael Ellerman
2020-03-06 0:27 ` [PATCH 1/6] powerpc: kernel: " Michael Ellerman
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