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Mon, 12 Feb 2024 22:17:10 -0800 (PST) From: Joe Damato To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: chuck.lever@oracle.com, jlayton@kernel.org, linux-api@vger.kernel.org, brauner@kernel.org, edumazet@google.com, davem@davemloft.net, alexander.duyck@gmail.com, sridhar.samudrala@intel.com, kuba@kernel.org, willemdebruijn.kernel@gmail.com, weiwan@google.com, David.Laight@ACULAB.COM, arnd@arndb.de, sdf@google.com, amritha.nambiar@intel.com, Joe Damato , Jiri Slaby , Jonathan Corbet , Alexander Viro , Jan Kara , Michael Ellerman , Greg Kroah-Hartman , Nathan Lynch , Thomas Zimmermann , Julien Panis , Steve French , Palmer Dabbelt , linux-doc@vger.kernel.org (open list:DOCUMENTATION), linux-fsdevel@vger.kernel.org (open list:FILESYSTEMS (VFS and infrastructure)) Subject: [PATCH net-next v8 4/4] eventpoll: Add epoll ioctl for epoll_params Date: Tue, 13 Feb 2024 06:16:45 +0000 Message-Id: <20240213061652.6342-5-jdamato@fastly.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240213061652.6342-1-jdamato@fastly.com> References: <20240213061652.6342-1-jdamato@fastly.com> Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Acked-by: Stanislav Fomichev Reviewed-by: Jiri Slaby --- .../userspace-api/ioctl/ioctl-number.rst | 1 + fs/eventpoll.c | 73 +++++++++++++++++++ include/uapi/linux/eventpoll.h | 13 ++++ 3 files changed, 87 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 diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 1b8d01af0c2c..df2ed3af486e 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -37,6 +37,7 @@ #include #include #include +#include #include /* @@ -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; + + WRITE_ONCE(ep->busy_poll_usecs, epoll_params.busy_poll_usecs); + WRITE_ONCE(ep->busy_poll_budget, epoll_params.busy_poll_budget); + WRITE_ONCE(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 = READ_ONCE(ep->busy_poll_usecs); + epoll_params.busy_poll_budget = READ_ONCE(ep->busy_poll_budget); + epoll_params.prefer_busy_poll = READ_ONCE(ep->prefer_busy_poll); + if (copy_to_user(uarg, &epoll_params, sizeof(epoll_params))) + return -EFAULT; + return 0; + default: + return -ENOIOCTLCMD; + } +} + #else static inline bool ep_busy_loop(struct eventpoll *ep, int nonblock) @@ -505,6 +549,12 @@ static inline void ep_set_busy_poll_napi_id(struct epitem *epi) { } +static long ep_eventpoll_bp_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + return -EOPNOTSUPP; +} + #endif /* CONFIG_NET_RX_BUSY_POLL */ /* @@ -864,6 +914,27 @@ static void ep_clear_and_put(struct eventpoll *ep) ep_free(ep); } +static long ep_eventpoll_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + int ret; + + if (!is_file_epoll(file)) + return -EINVAL; + + switch (cmd) { + case EPIOCSPARAMS: + case EPIOCGPARAMS: + ret = ep_eventpoll_bp_ioctl(file, cmd, arg); + break; + default: + ret = -EINVAL; + break; + } + + return ret; +} + static int ep_eventpoll_release(struct inode *inode, struct file *file) { struct eventpoll *ep = file->private_data; @@ -970,6 +1041,8 @@ static const struct file_operations eventpoll_fops = { .release = ep_eventpoll_release, .poll = ep_eventpoll_poll, .llseek = noop_llseek, + .unlocked_ioctl = ep_eventpoll_ioctl, + .compat_ioctl = compat_ptr_ioctl, }; /* diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h index cfbcc4cc49ac..4f4b948ef381 100644 --- a/include/uapi/linux/eventpoll.h +++ b/include/uapi/linux/eventpoll.h @@ -85,4 +85,17 @@ struct epoll_event { __u64 data; } EPOLL_PACKED; +struct epoll_params { + __u32 busy_poll_usecs; + __u16 busy_poll_budget; + __u8 prefer_busy_poll; + + /* pad the struct to a multiple of 64bits */ + __u8 __pad; +}; + +#define EPOLL_IOC_TYPE 0x8A +#define EPIOCSPARAMS _IOW(EPOLL_IOC_TYPE, 0x01, struct epoll_params) +#define EPIOCGPARAMS _IOR(EPOLL_IOC_TYPE, 0x02, struct epoll_params) + #endif /* _UAPI_LINUX_EVENTPOLL_H */ -- 2.25.1