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[104.53.165.62]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8ae33fe81fdsm41210467b3.47.2026.10.05.08.09.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Oct 2026 08:09:48 -0700 (PDT) From: Andrew Halaney Date: Mon, 05 Oct 2026 10:09:31 -0500 Subject: [PATCH v4 01/10] pid: add helpers to operate on a struct pid array Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261005-work-unix-passpidfd-v4-1-350183b6e02a@amutable.com> References: <20261005-work-unix-passpidfd-v4-0-350183b6e02a@amutable.com> In-Reply-To: <20261005-work-unix-passpidfd-v4-0-350183b6e02a@amutable.com> To: Jakub Kicinski , Kuniyuki Iwashima , Oleg Nesterov Cc: "David S. Miller" , Paolo Abeni , Simon Horman , Willem de Bruijn , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Alexander Viro , Jan Kara , linux-fsdevel@vger.kernel.org, Alexander Mikhalitsyn , "Christian Brauner (Amutable)" , Andrew Halaney , Eric Dumazet , Alexander Mikhalitsyn X-Mailer: b4 0.14.3 From: Christian Brauner We're about to extend af_unix sockets and coredump code with the ability to hand out thread-specific pidfds. Add a few simple helpers that allow to operate on multiple struct pids up to PIDTYPE_MAX with automatic bounds checking. Signed-off-by: Christian Brauner (Amutable) Reviewed-by: Alexander Mikhalitsyn Reviewed-by: Kuniyuki Iwashima Signed-off-by: Andrew Halaney --- fs/pidfs.c | 16 +++++++++++ include/linux/pid.h | 53 +++++++++++++++++++++++++++++++++++ include/linux/pid_types.h | 8 ++++++ include/linux/pidfs.h | 5 ++++ include/linux/sched/signal.h | 18 ++++++++++++ tools/lib/python/kdoc/xforms_lists.py | 1 + 6 files changed, 101 insertions(+) diff --git a/fs/pidfs.c b/fs/pidfs.c index a6a643f15d08..586af2e5811c 100644 --- a/fs/pidfs.c +++ b/fs/pidfs.c @@ -1070,6 +1070,22 @@ int pidfs_register_pid_gfp(struct pid *pid, gfp_t gfp) return 0; } +/* Register the pids up to pid type @last of @pids in pidfs. */ +int __pidfs_register_pids(struct pid *const *pids, enum pid_type last) +{ + if (WARN_ON_ONCE(last >= PIDTYPE_MAX)) + return -EINVAL; + + for (enum pid_type type = PIDTYPE_PID; type <= last; type++) { + int ret = pidfs_register_pid(pids[type]); + + if (unlikely(ret)) + return ret; + } + + return 0; +} + static struct dentry *pidfs_stash_dentry(struct dentry **stashed, struct dentry *dentry) { diff --git a/include/linux/pid.h b/include/linux/pid.h index ddaef0bbc8ba..87635d0cc1f7 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -2,6 +2,9 @@ #ifndef _LINUX_PID_H #define _LINUX_PID_H +#include +#include +#include #include #include #include @@ -92,6 +95,56 @@ static inline struct pid *get_pid(struct pid *pid) } extern void put_pid(struct pid *pid); + +/* + * Helpers for arrays of struct pid indexed by pid type declared with + * DECLARE_PIDS(). The array covers PIDTYPE_PID up to the pid type it + * was declared with and the helpers take that bound from the array. + */ +static inline void __get_pids(struct pid **dst, struct pid *const *src, + enum pid_type last) +{ + for (enum pid_type type = PIDTYPE_PID; type <= last; type++) + dst[type] = get_pid(src[type]); +} + +static inline void __put_pids(struct pid **pids, enum pid_type last) +{ + for (enum pid_type type = PIDTYPE_PID; type <= last; type++) { + put_pid(pids[type]); + pids[type] = NULL; + } +} + +static inline void __swap_pids(struct pid **a, struct pid **b, + enum pid_type last) +{ + for (enum pid_type type = PIDTYPE_PID; type <= last; type++) + swap(a[type], b[type]); +} + +static inline bool __pids_equal(struct pid *const *a, struct pid *const *b, + enum pid_type last) +{ + for (enum pid_type type = PIDTYPE_PID; type <= last; type++) + if (a[type] != b[type]) + return false; + return true; +} + +/* The last pid type an array declared with DECLARE_PIDS() covers. */ +#define pids_last(pids) \ + ((enum pid_type)(ARRAY_SIZE(pids) - 1 + \ + BUILD_BUG_ON_ZERO(ARRAY_SIZE(pids) > PIDTYPE_MAX))) + +#define __pids_last2(a, b) \ + (pids_last(a) + BUILD_BUG_ON_ZERO(ARRAY_SIZE(a) != ARRAY_SIZE(b))) + +#define get_pids(dst, src) __get_pids(dst, src, __pids_last2(dst, src)) +#define put_pids(pids) __put_pids(pids, pids_last(pids)) +#define swap_pids(a, b) __swap_pids(a, b, __pids_last2(a, b)) +#define pids_equal(a, b) __pids_equal(a, b, __pids_last2(a, b)) + extern struct task_struct *pid_task(struct pid *pid, enum pid_type); static inline bool pid_has_task(struct pid *pid, enum pid_type type) { diff --git a/include/linux/pid_types.h b/include/linux/pid_types.h index c2aee1d91dcf..3302690a2a28 100644 --- a/include/linux/pid_types.h +++ b/include/linux/pid_types.h @@ -2,6 +2,8 @@ #ifndef _LINUX_PID_TYPES_H #define _LINUX_PID_TYPES_H +#include + enum pid_type { PIDTYPE_PID, PIDTYPE_TGID, @@ -10,6 +12,12 @@ enum pid_type { PIDTYPE_MAX, }; +struct pid; + +/* An array of struct pid indexed by pid type, PIDTYPE_PID up to @last. */ +#define DECLARE_PIDS(name, last) \ + struct pid *name[(last) + 1 + BUILD_BUG_ON_ZERO((last) >= PIDTYPE_MAX)] + struct pid_namespace; extern struct pid_namespace init_pid_ns; diff --git a/include/linux/pidfs.h b/include/linux/pidfs.h index 0abf7da9ab23..3c1e82f1a369 100644 --- a/include/linux/pidfs.h +++ b/include/linux/pidfs.h @@ -3,6 +3,7 @@ #define _LINUX_PID_FS_H #include +#include struct coredump_params; @@ -32,5 +33,9 @@ static inline int pidfs_register_pid(struct pid *pid) } void pidfs_free_pid(struct pid *pid); +int __pidfs_register_pids(struct pid *const *pids, enum pid_type last); + +/* Register the pids of an array declared with DECLARE_PIDS(). */ +#define pidfs_register_pids(pids) __pidfs_register_pids(pids, pids_last(pids)) #endif /* _LINUX_PID_FS_H */ diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index d45a5476b97d..3149cdb976c6 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -674,6 +674,24 @@ struct pid *task_pid_type(struct task_struct *task, enum pid_type type) return pid; } +/* Fill @pids with the pid types of @task up to @last, without references. */ +static inline void __task_pids(struct pid **pids, enum pid_type last, + struct task_struct *task) +{ + for (enum pid_type type = PIDTYPE_PID; type <= last; type++) + pids[type] = task_pid_type(task, type); +} + +static inline void __get_task_pids(struct pid **pids, enum pid_type last, + struct task_struct *task) +{ + for (enum pid_type type = PIDTYPE_PID; type <= last; type++) + pids[type] = get_pid(task_pid_type(task, type)); +} + +#define task_pids(pids, task) __task_pids(pids, pids_last(pids), task) +#define get_task_pids(pids, task) __get_task_pids(pids, pids_last(pids), task) + static inline struct pid *task_tgid(struct task_struct *task) { return task->signal->pids[PIDTYPE_TGID]; diff --git a/tools/lib/python/kdoc/xforms_lists.py b/tools/lib/python/kdoc/xforms_lists.py index e3dda2fe8a53..e792785a15ec 100644 --- a/tools/lib/python/kdoc/xforms_lists.py +++ b/tools/lib/python/kdoc/xforms_lists.py @@ -45,6 +45,7 @@ class CTransforms: (CMatch("DECLARE_HASHTABLE"), r"unsigned long \1[1 << ((\2) - 1)]"), (CMatch("DECLARE_KFIFO"), r"\2 *\1"), (CMatch("DECLARE_KFIFO_PTR"), r"\2 *\1"), + (CMatch("DECLARE_PIDS"), r"struct pid *\1[(\2) + 1]"), (CMatch("(?:__)?DECLARE_FLEX_ARRAY"), r"\1 \2[]"), (CMatch("DEFINE_DMA_UNMAP_ADDR"), r"dma_addr_t \1"), (CMatch("DEFINE_DMA_UNMAP_LEN"), r"__u32 \1"), -- 2.55.0