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Message-Id: <20231026121621.358388-1-singhabhinav9051571833@gmail.com> Date: Thu, 26 Oct 2023 17:46:21 +0530 From: Abhinav Singh <singhabhinav9051571833@...il.com> To: akpm@...ux-foundation.org, brauner@...nel.org, surenb@...gle.com, mst@...hat.com, michael.christie@...cle.com, mathieu.desnoyers@...icios.com, mjguzik@...il.com, npiggin@...il.com, shakeelb@...gle.com, peterz@...radead.org Cc: linux-kernel@...r.kernel.org, linux-kernel-mentees@...ts.linuxfoundation.org, Abhinav Singh <singhabhinav9051571833@...il.com> Subject: [PATCH v2] Fixing directly deferencing a __rcu pointer warning This patch fixes the warning about directly dereferencing a pointer tagged with __rcu annotation. Dereferencing the pointers tagged with __rcu directly should always be avoided according to the docs. There is a rcu helper functions rcu_dereference(...) to use when dereferencing a __rcu pointer. This functions returns the non __rcu tagged pointer which can be dereferenced just like a normal pointers. Signed-off-by: Abhinav Singh <singhabhinav9051571833@...il.com> --- kernel/fork.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index 10917c3e1f03..802b7bbe3d92 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2369,7 +2369,7 @@ __latent_entropy struct task_struct *copy_process( retval = -EAGAIN; if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) { - if (p->real_cred->user != INIT_USER && + if (rcu_dereference(p->real_cred)->user != INIT_USER && !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) goto bad_fork_cleanup_count; } @@ -2692,7 +2692,7 @@ __latent_entropy struct task_struct *copy_process( */ p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper || p->real_parent->signal->is_child_subreaper; - list_add_tail(&p->sibling, &p->real_parent->children); + list_add_tail(&p->sibling, &(rcu_dereference(p->real_parent)->children)); list_add_tail_rcu(&p->tasks, &init_task.tasks); attach_pid(p, PIDTYPE_TGID); attach_pid(p, PIDTYPE_PGID); -- 2.39.2
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