Messages in this thread | | | From | Weiping Zhang <> | Date | Mon, 28 Dec 2020 22:10:03 +0800 | Subject | Re: [RFC PATCH v2] taskstats: add /proc/taskstats to fetch pid/tgid status |
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Hi David,
Could you help review this patch ?
thanks
On Fri, Dec 18, 2020 at 1:24 AM Weiping Zhang <zhangweiping@didiglobal.com> wrote: > > If a program needs monitor lots of process's status, it needs two > syscalls for every process. The first one is telling kernel which > pid/tgid should be monitored by send a command(write socket) to kernel. > The second one is read the statistics by read socket. This patch add > a new interface /proc/taskstats to reduce two syscalls to one ioctl. > The user just set the target pid/tgid to the struct taskstats.ac_pid, > then kernel will collect statistics for that pid/tgid. > > Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com> > --- > Changes since v1: > * use /proc/taskstats instead of /dev/taskstats > > include/uapi/linux/taskstats.h | 5 +++ > kernel/taskstats.c | 73 +++++++++++++++++++++++++++++++++- > 2 files changed, 77 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/taskstats.h b/include/uapi/linux/taskstats.h > index ccbd08709321..077eab84c77e 100644 > --- a/include/uapi/linux/taskstats.h > +++ b/include/uapi/linux/taskstats.h > @@ -214,6 +214,11 @@ enum { > > #define TASKSTATS_CMD_ATTR_MAX (__TASKSTATS_CMD_ATTR_MAX - 1) > > +/* ioctl command */ > +#define TASKSTATS_IOC_ATTR_PID _IO('T', TASKSTATS_CMD_ATTR_PID) > +#define TASKSTATS_IOC_ATTR_TGID _IO('T', TASKSTATS_CMD_ATTR_TGID) > + > + > /* NETLINK_GENERIC related info */ > > #define TASKSTATS_GENL_NAME "TASKSTATS" > diff --git a/kernel/taskstats.c b/kernel/taskstats.c > index a2802b6ff4bb..c0f9e2f2308b 100644 > --- a/kernel/taskstats.c > +++ b/kernel/taskstats.c > @@ -21,6 +21,8 @@ > #include <net/genetlink.h> > #include <linux/atomic.h> > #include <linux/sched/cputime.h> > +#include <linux/proc_fs.h> > +#include <linux/uio.h> > > /* > * Maximum length of a cpumask that can be specified in > @@ -28,6 +30,10 @@ > */ > #define TASKSTATS_CPUMASK_MAXLEN (100+6*NR_CPUS) > > +#ifdef CONFIG_PROC_FS > +#define PROC_TASKSTATS "taskstats" > +#endif > + > static DEFINE_PER_CPU(__u32, taskstats_seqnum); > static int family_registered; > struct kmem_cache *taskstats_cache; > @@ -666,6 +672,60 @@ static struct genl_family family __ro_after_init = { > .n_ops = ARRAY_SIZE(taskstats_ops), > }; > > +#ifdef CONFIG_PROC_FS > +static long taskstats_ioctl_pid_tgid(unsigned long arg, bool tgid) > +{ > + struct taskstats kstat; > + struct taskstats *ustat = (struct taskstats *)arg; > + u32 id; > + unsigned long offset = offsetof(struct taskstats, ac_pid); > + long ret; > + > + /* userspace set monitored pid/tgid to the field "ac_pid" */ > + if (unlikely(copy_from_user(&id, (void *)(arg + offset), sizeof(u32)))) > + return -EFAULT; > + > + if (tgid) > + ret = fill_stats_for_tgid(id, &kstat); > + else > + ret = fill_stats_for_pid(id, &kstat); > + if (ret < 0) > + return ret; > + > + if (unlikely(copy_to_user(ustat, &kstat, sizeof(struct taskstats)))) > + return -EFAULT; > + > + return 0; > +} > + > +static long taskstats_ioctl(struct file *file, unsigned int cmd, unsigned long arg) > +{ > + long ret; > + > + switch (cmd) { > + case TASKSTATS_IOC_ATTR_PID: > + ret = taskstats_ioctl_pid_tgid(arg, false); > + break; > + case TASKSTATS_IOC_ATTR_TGID: > + ret = taskstats_ioctl_pid_tgid(arg, true); > + break; > + default: > + ret = -EINVAL; > + break; > + } > + > + return ret; > +} > + > +static const struct proc_ops taskstats_proc_ops = { > + .proc_ioctl = taskstats_ioctl, > +#ifdef CONFIG_COMPAT > + .proc_compat_ioctl = taskstats_ioctl, > +#endif > +}; > +#endif > + > + > /* Needed early in initialization */ > void __init taskstats_init_early(void) > { > @@ -682,9 +742,20 @@ static int __init taskstats_init(void) > { > int rc; > > +#ifdef CONFIG_PROC_FS > + if (!proc_create(PROC_TASKSTATS, 0, NULL, &taskstats_proc_ops)) { > + pr_err("failed to create /proc/%s\n", PROC_TASKSTATS); > + return -1; > + } > +#endif > + > rc = genl_register_family(&family); > - if (rc) > + if (rc) { > +#ifdef CONFIG_PROC_FS > + remove_proc_entry(PROC_TASKSTATS, NULL); > +#endif > return rc; > + } > > family_registered = 1; > pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION); > -- > 2.17.2 >
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