On Fri, Feb 9, 2024 at 10:15 PM Joe Damato <jdamato@xxxxxxxxxx> wrote: > > Add an ioctl for getting and setting epoll_params. User programs can use > this ioctl to get and set the busy poll usec time, packet budget, and > prefer busy poll params for a specific epoll context. > > Parameters are limited: > - busy_poll_usecs is limited to <= s32_max > - busy_poll_budget is limited to <= NAPI_POLL_WEIGHT by unprivileged > users (!capable(CAP_NET_ADMIN)) > - prefer_busy_poll must be 0 or 1 > - __pad must be 0 > > Signed-off-by: Joe Damato <jdamato@xxxxxxxxxx> > Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx> > Reviewed-by: Jiri Slaby <jirislaby@xxxxxxxxxx> > --- > .../userspace-api/ioctl/ioctl-number.rst | 1 + > fs/eventpoll.c | 72 +++++++++++++++++++ > include/uapi/linux/eventpoll.h | 13 ++++ > 3 files changed, 86 insertions(+) > > diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst > index 457e16f06e04..b33918232f78 100644 > --- a/Documentation/userspace-api/ioctl/ioctl-number.rst > +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst > @@ -309,6 +309,7 @@ Code Seq# Include File Comments > 0x89 0B-DF linux/sockios.h > 0x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range > 0x89 F0-FF linux/sockios.h SIOCDEVPRIVATE range > +0x8A 00-1F linux/eventpoll.h > 0x8B all linux/wireless.h > 0x8C 00-3F WiNRADiO driver > <http://www.winradio.com.au/> > diff --git a/fs/eventpoll.c b/fs/eventpoll.c > index 1b8d01af0c2c..aa58d42737e6 100644 > --- a/fs/eventpoll.c > +++ b/fs/eventpoll.c > @@ -37,6 +37,7 @@ > #include <linux/seq_file.h> > #include <linux/compat.h> > #include <linux/rculist.h> > +#include <linux/capability.h> > #include <net/busy_poll.h> > > /* > @@ -494,6 +495,49 @@ static inline void ep_set_busy_poll_napi_id(struct epitem *epi) > ep->napi_id = napi_id; > } > > +static long ep_eventpoll_bp_ioctl(struct file *file, unsigned int cmd, > + unsigned long arg) > +{ > + struct eventpoll *ep = file->private_data; > + void __user *uarg = (void __user *)arg; > + struct epoll_params epoll_params; > + > + switch (cmd) { > + case EPIOCSPARAMS: > + if (copy_from_user(&epoll_params, uarg, sizeof(epoll_params))) > + return -EFAULT; > + > + /* pad byte must be zero */ > + if (epoll_params.__pad) > + return -EINVAL; > + > + if (epoll_params.busy_poll_usecs > S32_MAX) > + return -EINVAL; > + > + if (epoll_params.prefer_busy_poll > 1) > + return -EINVAL; > + > + if (epoll_params.busy_poll_budget > NAPI_POLL_WEIGHT && > + !capable(CAP_NET_ADMIN)) > + return -EPERM; > + > + ep->busy_poll_usecs = epoll_params.busy_poll_usecs; You need WRITE_ONCE(ep->XXX, val); for all these settings. > + ep->busy_poll_budget = epoll_params.busy_poll_budget; > + ep->prefer_busy_poll = epoll_params.prefer_busy_poll; > + return 0; > + case EPIOCGPARAMS: > + memset(&epoll_params, 0, sizeof(epoll_params)); > + epoll_params.busy_poll_usecs = ep->busy_poll_usecs; You need to use READ_ONCE(ep->XXXXX) for the three reads. > + epoll_params.busy_poll_budget = ep->busy_poll_budget; > + epoll_params.prefer_busy_poll = ep->prefer_busy_poll; > + if (copy_to_user(uarg, &epoll_params, sizeof(epoll_params))) > + return -EFAULT; > + return 0; > + default: > + return -ENOIOCTLCMD; > + } > +} >
