2017-07-24 11:40:17

by Claudio Imbrenda

Subject: [PATCH v2 1/1] KVM: make pid available for uevents without debugfs

Simplify and improve the code so that the PID is always available in
the uevent even when debugfs is not available.

This adds a userspace_pid field to struct kvm, as per Radim's
suggestion, so that the PID can be retrieved on destruction too.

Acked-by: Janosch Frank <[email protected]>
Fixes: 286de8f6ac9202 ("KVM: trigger uevents when creating or destroying a VM")
Signed-off-by: Claudio Imbrenda <[email protected]>
---
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 35 ++++++++++++-----------------------
2 files changed, 13 insertions(+), 23 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 648b34c..890b706 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -445,6 +445,7 @@ struct kvm {
struct kvm_stat_data **debugfs_stat_data;
struct srcu_struct srcu;
struct srcu_struct irq_srcu;
+ pid_t userspace_pid;
};

#define kvm_err(fmt, ...) \
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 82987d4..f3f7427 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3883,7 +3883,6 @@ static const struct file_operations *stat_fops[] = {
static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
{
struct kobj_uevent_env *env;
- char *tmp, *pathbuf = NULL;
unsigned long long created, active;

if (!kvm_dev.this_device || !kvm)
@@ -3907,38 +3906,28 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
add_uevent_var(env, "CREATED=%llu", created);
add_uevent_var(env, "COUNT=%llu", active);

- if (type == KVM_EVENT_CREATE_VM)
+ if (type == KVM_EVENT_CREATE_VM) {
add_uevent_var(env, "EVENT=create");
- else if (type == KVM_EVENT_DESTROY_VM)
+ kvm->userspace_pid = task_pid_nr(current);
+ } else if (type == KVM_EVENT_DESTROY_VM) {
add_uevent_var(env, "EVENT=destroy");
+ }
+ add_uevent_var(env, "PID=%d", kvm->userspace_pid);

if (kvm->debugfs_dentry) {
- char p[ITOA_MAX_LEN];
-
- snprintf(p, sizeof(p), "%s", kvm->debugfs_dentry->d_name.name);
- tmp = strchrnul(p + 1, '-');
- *tmp = '\0';
- add_uevent_var(env, "PID=%s", p);
- pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
- if (pathbuf) {
- /* sizeof counts the final '\0' */
- int len = sizeof("STATS_PATH=") - 1;
- const char *pvar = "STATS_PATH=";
-
- tmp = dentry_path_raw(kvm->debugfs_dentry,
- pathbuf + len,
- PATH_MAX - len);
- if (!IS_ERR(tmp)) {
- memcpy(tmp - len, pvar, len);
- env->envp[env->envp_idx++] = tmp - len;
- }
+ char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL);
+
+ if (p) {
+ tmp = dentry_path_raw(kvm->debugfs_dentry, p, PATH_MAX);
+ if (!IS_ERR(tmp))
+ add_uevent_var(env, "STATS_PATH=%s", tmp);
+ kfree(p);
}
}
/* no need for checks, since we are adding at most only 5 keys */
env->envp[env->envp_idx++] = NULL;
kobject_uevent_env(&kvm_dev.this_device->kobj, KOBJ_CHANGE, env->envp);
kfree(env);
- kfree(pathbuf);
}

static int kvm_init_debug(void)
--
2.7.4

2017-07-24 14:30:38

by Paolo Bonzini

Subject: Re: [PATCH v2 1/1] KVM: make pid available for uevents without debugfs

On 24/07/2017 13:40, Claudio Imbrenda wrote:
> Simplify and improve the code so that the PID is always available in
> the uevent even when debugfs is not available.
>
> This adds a userspace_pid field to struct kvm, as per Radim's
> suggestion, so that the PID can be retrieved on destruction too.
>
> Acked-by: Janosch Frank <[email protected]>
> Fixes: 286de8f6ac9202 ("KVM: trigger uevents when creating or destroying a VM")
> Signed-off-by: Claudio Imbrenda <[email protected]>
> ---
> include/linux/kvm_host.h | 1 +
> virt/kvm/kvm_main.c | 35 ++++++++++++-----------------------
> 2 files changed, 13 insertions(+), 23 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 648b34c..890b706 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -445,6 +445,7 @@ struct kvm {
> struct kvm_stat_data **debugfs_stat_data;
> struct srcu_struct srcu;
> struct srcu_struct irq_srcu;
> + pid_t userspace_pid;
> };
>
> #define kvm_err(fmt, ...) \
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 82987d4..f3f7427 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3883,7 +3883,6 @@ static const struct file_operations *stat_fops[] = {
> static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
> {
> struct kobj_uevent_env *env;
> - char *tmp, *pathbuf = NULL;
> unsigned long long created, active;
>
> if (!kvm_dev.this_device || !kvm)
> @@ -3907,38 +3906,28 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
> add_uevent_var(env, "CREATED=%llu", created);
> add_uevent_var(env, "COUNT=%llu", active);
>
> - if (type == KVM_EVENT_CREATE_VM)
> + if (type == KVM_EVENT_CREATE_VM) {
> add_uevent_var(env, "EVENT=create");
> - else if (type == KVM_EVENT_DESTROY_VM)
> + kvm->userspace_pid = task_pid_nr(current);
> + } else if (type == KVM_EVENT_DESTROY_VM) {
> add_uevent_var(env, "EVENT=destroy");
> + }
> + add_uevent_var(env, "PID=%d", kvm->userspace_pid);
>
> if (kvm->debugfs_dentry) {
> - char p[ITOA_MAX_LEN];
> -
> - snprintf(p, sizeof(p), "%s", kvm->debugfs_dentry->d_name.name);
> - tmp = strchrnul(p + 1, '-');
> - *tmp = '\0';
> - add_uevent_var(env, "PID=%s", p);
> - pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
> - if (pathbuf) {
> - /* sizeof counts the final '\0' */
> - int len = sizeof("STATS_PATH=") - 1;
> - const char *pvar = "STATS_PATH=";
> -
> - tmp = dentry_path_raw(kvm->debugfs_dentry,
> - pathbuf + len,
> - PATH_MAX - len);
> - if (!IS_ERR(tmp)) {
> - memcpy(tmp - len, pvar, len);
> - env->envp[env->envp_idx++] = tmp - len;
> - }
> + char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL);
> +
> + if (p) {
> + tmp = dentry_path_raw(kvm->debugfs_dentry, p, PATH_MAX);
> + if (!IS_ERR(tmp))
> + add_uevent_var(env, "STATS_PATH=%s", tmp);
> + kfree(p);
> }
> }
> /* no need for checks, since we are adding at most only 5 keys */
> env->envp[env->envp_idx++] = NULL;
> kobject_uevent_env(&kvm_dev.this_device->kobj, KOBJ_CHANGE, env->envp);
> kfree(env);
> - kfree(pathbuf);
> }
>
> static int kvm_init_debug(void)
>

Looks good, thanks.

Paolo

2017-07-24 18:03:47

by David Hildenbrand

Subject: Re: [PATCH v2 1/1] KVM: make pid available for uevents without debugfs

On 24.07.2017 13:40, Claudio Imbrenda wrote:
> Simplify and improve the code so that the PID is always available in
> the uevent even when debugfs is not available.
>
> This adds a userspace_pid field to struct kvm, as per Radim's
> suggestion, so that the PID can be retrieved on destruction too.
>
> Acked-by: Janosch Frank <[email protected]>
> Fixes: 286de8f6ac9202 ("KVM: trigger uevents when creating or destroying a VM")
> Signed-off-by: Claudio Imbrenda <[email protected]>
> ---
> include/linux/kvm_host.h | 1 +
> virt/kvm/kvm_main.c | 35 ++++++++++++-----------------------
> 2 files changed, 13 insertions(+), 23 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 648b34c..890b706 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -445,6 +445,7 @@ struct kvm {
> struct kvm_stat_data **debugfs_stat_data;
> struct srcu_struct srcu;
> struct srcu_struct irq_srcu;
> + pid_t userspace_pid;
> };
>
> #define kvm_err(fmt, ...) \
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 82987d4..f3f7427 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3883,7 +3883,6 @@ static const struct file_operations *stat_fops[] = {
> static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
> {
> struct kobj_uevent_env *env;
> - char *tmp, *pathbuf = NULL;
> unsigned long long created, active;
>
> if (!kvm_dev.this_device || !kvm)
> @@ -3907,38 +3906,28 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
> add_uevent_var(env, "CREATED=%llu", created);
> add_uevent_var(env, "COUNT=%llu", active);
>
> - if (type == KVM_EVENT_CREATE_VM)
> + if (type == KVM_EVENT_CREATE_VM) {
> add_uevent_var(env, "EVENT=create");
> - else if (type == KVM_EVENT_DESTROY_VM)
> + kvm->userspace_pid = task_pid_nr(current);
> + } else if (type == KVM_EVENT_DESTROY_VM) {
> add_uevent_var(env, "EVENT=destroy");
> + }
> + add_uevent_var(env, "PID=%d", kvm->userspace_pid);
>
> if (kvm->debugfs_dentry) {
> - char p[ITOA_MAX_LEN];
> -
> - snprintf(p, sizeof(p), "%s", kvm->debugfs_dentry->d_name.name);
> - tmp = strchrnul(p + 1, '-');
> - *tmp = '\0';
> - add_uevent_var(env, "PID=%s", p);
> - pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
> - if (pathbuf) {
> - /* sizeof counts the final '\0' */
> - int len = sizeof("STATS_PATH=") - 1;
> - const char *pvar = "STATS_PATH=";
> -
> - tmp = dentry_path_raw(kvm->debugfs_dentry,
> - pathbuf + len,
> - PATH_MAX - len);
> - if (!IS_ERR(tmp)) {
> - memcpy(tmp - len, pvar, len);
> - env->envp[env->envp_idx++] = tmp - len;
> - }
> + char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL);
> +
> + if (p) {
> + tmp = dentry_path_raw(kvm->debugfs_dentry, p, PATH_MAX);
> + if (!IS_ERR(tmp))
> + add_uevent_var(env, "STATS_PATH=%s", tmp);
> + kfree(p);
> }
> }
> /* no need for checks, since we are adding at most only 5 keys */
> env->envp[env->envp_idx++] = NULL;
> kobject_uevent_env(&kvm_dev.this_device->kobj, KOBJ_CHANGE, env->envp);
> kfree(env);
> - kfree(pathbuf);
> }
>
> static int kvm_init_debug(void)
>

Yes, much better!

Reviewed-by: David Hildenbrand <[email protected]>

--

Thanks,

David