| Message ID | 20200209105901.1620958-2-gregkh@linuxfoundation.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | c4fd527f52ecb135018655c7f56f87800872c5bc |
| Headers | show |
| Series | [1/6] powerpc: kernel: no need to check return value of debugfs_create functions | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (a5bc6e124219546a81ce334dc9b16483d55e9abf) |
| snowpatch_ozlabs/checkpatch | fail | total: 1 errors, 1 warnings, 0 checks, 75 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
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
On Tue, Mar 03, 2020 at 06:46:23PM +1100, Michael Ellerman wrote: > 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; Ugh, you are right, how did I miss that? How is 0-day missing this? It's been in my tree for a long time, odd. > > } > > 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; That works, yes. > } > > 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; > } No, this can just be: debugfs_remove(vcpu->arch.debugfs_exit_timing); No need to check anything, just call it and the debugfs code can handle it just fine. thanks, greg k-h
Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes: > On Tue, Mar 03, 2020 at 06:46:23PM +1100, Michael Ellerman wrote: >> 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; > > Ugh, you are right, how did I miss that? How is 0-day missing this? > It's been in my tree for a long time, odd. This code isn't enabled by default, or in any defconfig. So it's only allmodconfig that would trip it, I guess 0-day isn't doing powerpc allmodconfig builds. >> I squashed this in, which seems to work: ... >> >> 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; >> } > > No, this can just be: > debugfs_remove(vcpu->arch.debugfs_exit_timing); > > No need to check anything, just call it and the debugfs code can handle > it just fine. Oh duh, of course, I should have checked. I'd still like to NULL out the debugfs_exit_timing member, so I'll do: void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu) { debugfs_remove(vcpu->arch.debugfs_exit_timing); vcpu->arch.debugfs_exit_timing = NULL; } cheers
On Tue, Mar 03, 2020 at 08:45:23PM +1100, Michael Ellerman wrote: > Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes: > > On Tue, Mar 03, 2020 at 06:46:23PM +1100, Michael Ellerman wrote: > >> 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; > > > > Ugh, you are right, how did I miss that? How is 0-day missing this? > > It's been in my tree for a long time, odd. > > This code isn't enabled by default, or in any defconfig. So it's only > allmodconfig that would trip it, I guess 0-day isn't doing powerpc > allmodconfig builds. > > >> I squashed this in, which seems to work: > ... > >> > >> 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; > >> } > > > > No, this can just be: > > debugfs_remove(vcpu->arch.debugfs_exit_timing); > > > > No need to check anything, just call it and the debugfs code can handle > > it just fine. > > Oh duh, of course, I should have checked. > > I'd still like to NULL out the debugfs_exit_timing member, so I'll do: > > void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu) > { > debugfs_remove(vcpu->arch.debugfs_exit_timing); > vcpu->arch.debugfs_exit_timing = NULL; > } Fair enough, but I doubt it ever matters :) Thanks for the fixups, sorry for sending a broken patch, my fault. greg k-h
Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes: > On Tue, Mar 03, 2020 at 08:45:23PM +1100, Michael Ellerman wrote: >> Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes: >> > On Tue, Mar 03, 2020 at 06:46:23PM +1100, Michael Ellerman wrote: >> >> 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; >> > >> > Ugh, you are right, how did I miss that? How is 0-day missing this? >> > It's been in my tree for a long time, odd. >> >> This code isn't enabled by default, or in any defconfig. So it's only >> allmodconfig that would trip it, I guess 0-day isn't doing powerpc >> allmodconfig builds. >> >> >> I squashed this in, which seems to work: >> ... >> >> >> >> 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; >> >> } >> > >> > No, this can just be: >> > debugfs_remove(vcpu->arch.debugfs_exit_timing); >> > >> > No need to check anything, just call it and the debugfs code can handle >> > it just fine. >> >> Oh duh, of course, I should have checked. >> >> I'd still like to NULL out the debugfs_exit_timing member, so I'll do: >> >> void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu) >> { >> debugfs_remove(vcpu->arch.debugfs_exit_timing); >> vcpu->arch.debugfs_exit_timing = NULL; >> } > > Fair enough, but I doubt it ever matters :) Yeah, but I'm paranoid and I have no way to test this code :) > Thanks for the fixups, sorry for sending a broken patch, my fault. No worries, we have too many CONFIG options. cheers
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 6e8b8ffd06ad..877f8aa2bc1e 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -308,8 +308,6 @@ struct kvm_arch { pgd_t *pgtable; u64 process_table; struct dentry *debugfs_dir; - struct dentry *htab_dentry; - struct dentry *radix_dentry; struct kvm_resize_hpt *resize_hpt; /* protected by kvm->lock */ #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE @@ -830,7 +828,6 @@ struct kvm_vcpu_arch { struct kvmhv_tb_accumulator cede_time; /* time napping inside guest */ struct dentry *debugfs_dir; - struct dentry *debugfs_timings; #endif /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */ }; diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 6c372f5c61b6..8b4eac0c9dcd 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -2138,9 +2138,8 @@ static const struct file_operations debugfs_htab_fops = { void kvmppc_mmu_debugfs_init(struct kvm *kvm) { - kvm->arch.htab_dentry = debugfs_create_file("htab", 0400, - kvm->arch.debugfs_dir, kvm, - &debugfs_htab_fops); + debugfs_create_file("htab", 0400, kvm->arch.debugfs_dir, kvm, + &debugfs_htab_fops); } void kvmppc_mmu_book3s_hv_init(struct kvm_vcpu *vcpu) diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index 803940d79b73..1d75ed684b53 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -1376,9 +1376,8 @@ static const struct file_operations debugfs_radix_fops = { void kvmhv_radix_debugfs_init(struct kvm *kvm) { - kvm->arch.radix_dentry = debugfs_create_file("radix", 0400, - kvm->arch.debugfs_dir, kvm, - &debugfs_radix_fops); + debugfs_create_file("radix", 0400, kvm->arch.debugfs_dir, kvm, + &debugfs_radix_fops); } int kvmppc_radix_init(void) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 2cefd071b848..33be4d93248a 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2258,14 +2258,9 @@ static void debugfs_vcpu_init(struct kvm_vcpu *vcpu, unsigned int id) struct kvm *kvm = vcpu->kvm; snprintf(buf, sizeof(buf), "vcpu%u", id); - if (IS_ERR_OR_NULL(kvm->arch.debugfs_dir)) - return; vcpu->arch.debugfs_dir = debugfs_create_dir(buf, kvm->arch.debugfs_dir); - if (IS_ERR_OR_NULL(vcpu->arch.debugfs_dir)) - return; - vcpu->arch.debugfs_timings = - debugfs_create_file("timings", 0444, vcpu->arch.debugfs_dir, - vcpu, &debugfs_timings_ops); + debugfs_create_file("timings", 0444, vcpu->arch.debugfs_dir, vcpu, + &debugfs_timings_ops); } #else /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */ 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; }
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. Because of this cleanup, we get to remove a few fields in struct kvm_arch that are now unused. Cc: Paul Mackerras <paulus@ozlabs.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: kvm-ppc@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/powerpc/include/asm/kvm_host.h | 3 --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 5 ++--- arch/powerpc/kvm/book3s_64_mmu_radix.c | 5 ++--- arch/powerpc/kvm/book3s_hv.c | 9 ++------- arch/powerpc/kvm/timing.c | 13 +++---------- 5 files changed, 9 insertions(+), 26 deletions(-)