From: "André Almeida" <andrealmeid@igalia.com>
To: Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Steven Rostedt <rostedt@goodmis.org>,
Christian Brauner <brauner@kernel.org>,
Kees Cook <kees@kernel.org>, Shuah Khan <shuah@kernel.org>,
willy@infradead.org, mathieu.desnoyers@efficios.com,
David Laight <david.laight.linux@gmail.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
akpm@linux-foundation.org, Yafang Shao <laoar.shao@gmail.com>,
andrii.nakryiko@gmail.com, arnaldo.melo@gmail.com,
Petr Mladek <pmladek@suse.com>
Cc: linux-kernel@vger.kernel.org, kernel-dev@igalia.com,
linux-mm@kvack.org, linux-api@vger.kernel.org,
linux-trace-kernel@vger.kernel.org,
"André Almeida" <andrealmeid@igalia.com>
Subject: [PATCH v7 2/6] treewide: Replace memcpy(..., current->comm) with copy_task_comm()
Date: Fri, 11 Sep 2026 22:23:59 -0300 [thread overview]
Message-ID: <20260911-tonyk-long_name-v7-2-34e1ee1564ae@igalia.com> (raw)
In-Reply-To: <20260911-tonyk-long_name-v7-0-34e1ee1564ae@igalia.com>
In order to increase the size of current->comm[] and to avoid breaking any
existing code, replace memcpy() with copy_task_comm(). This new function
makes sure that the copy is NUL terminated. This is crucial given that the
source buffer might be larger than the destination buffer and could
truncate the NUL character out of it.
Signed-off-by: André Almeida <andrealmeid@igalia.com>
---
Changes from v4:
- Remove copy_task_comm() calls for structs other than struct task_struct
- Add checks for len > TASK_COMM_LEN and len < 0
Changes from v3:
- Simplify copy_task_comm() to a memcpy + NUL char at the end of buffer
Changes from v2:
- Bring back custom function.
Changes from v1:
- New patch, dropped strtostr() from last version
---
include/linux/coredump.h | 2 +-
include/linux/sched.h | 15 +++++++++++++++
include/linux/tracepoint.h | 4 ++--
include/trace/events/block.h | 10 +++++-----
include/trace/events/coredump.h | 2 +-
include/trace/events/f2fs.h | 4 ++--
include/trace/events/oom.h | 2 +-
include/trace/events/osnoise.h | 2 +-
include/trace/events/sched.h | 10 +++++-----
include/trace/events/signal.h | 2 +-
include/trace/events/task.h | 4 ++--
.../testing/selftests/bpf/test_kmods/bpf_testmod-events.h | 2 +-
12 files changed, 37 insertions(+), 22 deletions(-)
diff --git a/include/linux/coredump.h b/include/linux/coredump.h
index 7b38ee2e7913..dee82e3c350a 100644
--- a/include/linux/coredump.h
+++ b/include/linux/coredump.h
@@ -58,7 +58,7 @@ extern void vfs_coredump(const kernel_siginfo_t *siginfo);
do { \
char comm[TASK_COMM_LEN]; \
/* This will always be NUL terminated. */ \
- memcpy(comm, current->comm, sizeof(comm)); \
+ copy_task_comm(comm, current, sizeof(comm)); \
printk_ratelimited(Level "coredump: %d(%*pE): " Format "\n", \
task_tgid_vnr(current), (int)strlen(comm), comm, ##__VA_ARGS__); \
} while (0) \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d7d3bbb205c9..ba2040566424 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2036,6 +2036,21 @@ extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec
__set_task_comm(tsk, from, false); \
})
+/*
+ * Copy task name to a buffer. Final result is always a NUL-terminated string.
+ */
+static __always_inline void copy_task_comm(char *dst, struct task_struct *tsk, size_t len)
+{
+ const char *_src = tsk->comm;
+ size_t _len = min(len, TASK_COMM_LEN);
+
+ if (!_len)
+ return;
+
+ memcpy(dst, _src, _len);
+ dst[_len - 1] = '\0';
+}
+
static __always_inline void scheduler_ipi(void)
{
/*
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index e0d838c9ce93..9b0094fa44c6 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -637,10 +637,10 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
* *
*
* TP_fast_assign(
- * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
+ * copy_task_comm(__entry->next_comm, next, TASK_COMM_LEN);
* __entry->prev_pid = prev->pid;
* __entry->prev_prio = prev->prio;
- * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
+ * copy_task_comm(__entry->prev_comm, prev, TASK_COMM_LEN);
* __entry->next_pid = next->pid;
* __entry->next_prio = next->prio;
* ),
diff --git a/include/trace/events/block.h b/include/trace/events/block.h
index 9c97a16850b9..1e3a9ded03bd 100644
--- a/include/trace/events/block.h
+++ b/include/trace/events/block.h
@@ -213,7 +213,7 @@ DECLARE_EVENT_CLASS(block_rq,
blk_fill_rwbs(__entry->rwbs, rq->cmd_flags);
__get_str(cmd)[0] = '\0';
- memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, current, TASK_COMM_LEN);
),
TP_printk("%d,%d %s %u (%s) %llu + %u %s,%u,%u [%s]",
@@ -410,7 +410,7 @@ DECLARE_EVENT_CLASS(block_bio,
__entry->sector = bio->bi_iter.bi_sector;
__entry->nr_sector = bio_sectors(bio);
blk_fill_rwbs(__entry->rwbs, bio->bi_opf);
- memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, current, TASK_COMM_LEN);
),
TP_printk("%d,%d %s %llu + %u [%s]",
@@ -493,7 +493,7 @@ TRACE_EVENT(block_plug,
),
TP_fast_assign(
- memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, current, TASK_COMM_LEN);
),
TP_printk("[%s]", __entry->comm)
@@ -512,7 +512,7 @@ DECLARE_EVENT_CLASS(block_unplug,
TP_fast_assign(
__entry->nr_rq = depth;
- memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, current, TASK_COMM_LEN);
),
TP_printk("[%s] %d", __entry->comm, __entry->nr_rq)
@@ -563,7 +563,7 @@ TRACE_EVENT(block_split,
__entry->sector = bio->bi_iter.bi_sector;
__entry->new_sector = new_sector;
blk_fill_rwbs(__entry->rwbs, bio->bi_opf);
- memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, current, TASK_COMM_LEN);
),
TP_printk("%d,%d %s %llu / %llu [%s]",
diff --git a/include/trace/events/coredump.h b/include/trace/events/coredump.h
index c7b9c53fc498..fdd20bc46bb0 100644
--- a/include/trace/events/coredump.h
+++ b/include/trace/events/coredump.h
@@ -32,7 +32,7 @@ TRACE_EVENT(coredump,
TP_fast_assign(
__entry->sig = sig;
- memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, current, TASK_COMM_LEN);
),
TP_printk("sig=%d comm=%s",
diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
index d53be932df01..faabc15b4a11 100644
--- a/include/trace/events/f2fs.h
+++ b/include/trace/events/f2fs.h
@@ -2518,7 +2518,7 @@ TRACE_EVENT(f2fs_lock_elapsed_time,
TP_fast_assign(
__entry->dev = sbi->sb->s_dev;
- memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, p, TASK_COMM_LEN);
__entry->pid = p->pid;
__entry->prio = p->prio;
__entry->ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
@@ -2571,7 +2571,7 @@ DECLARE_EVENT_CLASS(f2fs_priority_update,
TP_fast_assign(
__entry->dev = sbi->sb->s_dev;
- memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, p, TASK_COMM_LEN);
__entry->pid = p->pid;
__entry->lock_name = lock_name;
__entry->is_write = is_write;
diff --git a/include/trace/events/oom.h b/include/trace/events/oom.h
index 9f0a5d1482c4..8bcdc4ffc8d3 100644
--- a/include/trace/events/oom.h
+++ b/include/trace/events/oom.h
@@ -23,7 +23,7 @@ TRACE_EVENT(oom_score_adj_update,
TP_fast_assign(
__entry->pid = task->pid;
- memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, task, TASK_COMM_LEN);
__entry->oom_score_adj = task->signal->oom_score_adj;
),
diff --git a/include/trace/events/osnoise.h b/include/trace/events/osnoise.h
index 3f4273623801..2cf047bb9fb7 100644
--- a/include/trace/events/osnoise.h
+++ b/include/trace/events/osnoise.h
@@ -116,7 +116,7 @@ TRACE_EVENT(thread_noise,
),
TP_fast_assign(
- memcpy(__entry->comm, t->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, t, TASK_COMM_LEN);
__entry->pid = t->pid;
__entry->start = start;
__entry->duration = duration;
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 535860581f15..afb24e9dac91 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -152,7 +152,7 @@ DECLARE_EVENT_CLASS(sched_wakeup_template,
),
TP_fast_assign(
- memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, p, TASK_COMM_LEN);
__entry->pid = p->pid;
__entry->prio = p->prio; /* XXX SCHED_DEADLINE */
__entry->target_cpu = task_cpu(p);
@@ -237,11 +237,11 @@ TRACE_EVENT(sched_switch,
),
TP_fast_assign(
- memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->prev_comm, prev, TASK_COMM_LEN);
__entry->prev_pid = prev->pid;
__entry->prev_prio = prev->prio;
__entry->prev_state = __trace_sched_switch_state(preempt, prev_state, prev);
- memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->next_comm, next, TASK_COMM_LEN);
__entry->next_pid = next->pid;
__entry->next_prio = next->prio;
/* XXX SCHED_DEADLINE */
@@ -346,7 +346,7 @@ TRACE_EVENT(sched_process_exit,
),
TP_fast_assign(
- memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, p, TASK_COMM_LEN);
__entry->pid = p->pid;
__entry->prio = p->prio; /* XXX SCHED_DEADLINE */
__entry->group_dead = group_dead;
@@ -787,7 +787,7 @@ TRACE_EVENT(sched_skip_cpuset_numa,
),
TP_fast_assign(
- memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, tsk, TASK_COMM_LEN);
__entry->pid = task_pid_nr(tsk);
__entry->tgid = task_tgid_nr(tsk);
__entry->ngid = task_numa_group_id(tsk);
diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h
index 1db7e4b07c01..8fffe6d9bdcc 100644
--- a/include/trace/events/signal.h
+++ b/include/trace/events/signal.h
@@ -67,7 +67,7 @@ TRACE_EVENT(signal_generate,
TP_fast_assign(
__entry->sig = sig;
TP_STORE_SIGINFO(__entry, info);
- memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, task, TASK_COMM_LEN);
__entry->pid = task->pid;
__entry->group = group;
__entry->result = result;
diff --git a/include/trace/events/task.h b/include/trace/events/task.h
index b9a129eb54d9..e3faaeb997ef 100644
--- a/include/trace/events/task.h
+++ b/include/trace/events/task.h
@@ -21,7 +21,7 @@ TRACE_EVENT(task_newtask,
TP_fast_assign(
__entry->pid = task->pid;
- memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, task, TASK_COMM_LEN);
__entry->clone_flags = clone_flags;
__entry->oom_score_adj = task->signal->oom_score_adj;
),
@@ -46,7 +46,7 @@ TRACE_EVENT(task_rename,
TP_fast_assign(
__entry->pid = task->pid;
- memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
+ copy_task_comm(entry->oldcomm, task, TASK_COMM_LEN);
strscpy(entry->newcomm, comm, TASK_COMM_LEN);
__entry->oom_score_adj = task->signal->oom_score_adj;
),
diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
index 45a5e41f3a92..a197622e113c 100644
--- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
+++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod-events.h
@@ -20,7 +20,7 @@ TRACE_EVENT(bpf_testmod_test_read,
),
TP_fast_assign(
__entry->pid = task->pid;
- memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+ copy_task_comm(__entry->comm, task, TASK_COMM_LEN);
__entry->off = ctx->off;
__entry->len = ctx->len;
),
--
2.55.0
next prev parent reply other threads:[~2026-09-12 1:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-12 1:23 [PATCH v7 0/6] sched: Add support for long task name André Almeida
2026-09-12 1:23 ` [PATCH v7 1/6] treewide: Get rid of get_task_comm() André Almeida
2026-09-12 1:23 ` André Almeida [this message]
2026-09-12 1:24 ` [PATCH v7 3/6] lib/string_kunit: Add test for copy_task_comm() André Almeida
2026-09-12 1:24 ` [PATCH v7 4/6] sched: Extend task command name with TASK_COMM_EXT_LEN André Almeida
2026-09-12 1:24 ` [PATCH v7 5/6] prctl: Add support for long user thread names André Almeida
2026-09-12 1:24 ` [PATCH v7 6/6] selftests: prctl: Add test for long " André Almeida
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