linux-toradex.git/kernel/tracepoint.c, branch v7.0-rc6

Convert 'alloc_flex' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This is the exact same thing as the 'alloc_obj()' version, only much
smaller because there are a lot fewer users of the *alloc_flex()
interface.

As with alloc_obj() version, this was done entirely with mindless brute
force, using the same script, except using 'flex' in the pattern rather
than 'objs*'.

Signed-off-by: Linus Torvalds

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using

    git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook

tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast

2026-01-30T15:44:11+00:00

The current use of guard(preempt_notrace)() within __DECLARE_TRACE()
to protect invocation of __DO_TRACE_CALL() means that BPF programs
attached to tracepoints are non-preemptible.  This is unhelpful in
real-time systems, whose users apparently wish to use BPF while also
achieving low latencies.  (Who knew?)

One option would be to use preemptible RCU, but this introduces
many opportunities for infinite recursion, which many consider to
be counterproductive, especially given the relatively small stacks
provided by the Linux kernel.  These opportunities could be shut down
by sufficiently energetic duplication of code, but this sort of thing
is considered impolite in some circles.

Therefore, use the shiny new SRCU-fast API, which provides somewhat faster
readers than those of preemptible RCU, at least on Paul E. McKenney's
laptop, where task_struct access is more expensive than access to per-CPU
variables.  And SRCU-fast provides way faster readers than does SRCU,
courtesy of being able to avoid the read-side use of smp_mb().  Also,
it is quite straightforward to create srcu_read_{,un}lock_fast_notrace()
functions.

Link: https://lore.kernel.org/all/20250613152218.1924093-1-bigeasy@linutronix.de/

Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Cc: Sebastian Andrzej Siewior 
Cc: Alexei Starovoitov 
Link: https://patch.msgid.link/20260126231256.499701982@kernel.org
Co-developed-by: Paul E. McKenney 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Steven Rostedt (Google)

tracepoint: Print the function symbol when tracepoint_debug is set

2025-03-21T19:30:10+00:00

When tracepoint_debug is set, we may get the output in kernel log:
     [  380.013843] Probe 0 : 00000000f0d68cda

It is not readable, so change to print the function symbol.
After this patch, the output may becomes:
     [   55.225555] Probe 0 : perf_trace_sched_wakeup_template+0x0/0x20

Link: https://lore.kernel.org/20250307033858.4134-1-shijie@os.amperecomputing.com
Signed-off-by: Huang Shijie 
Signed-off-by: Steven Rostedt (Google)

tracing: Fix syscall tracepoint use-after-free

2024-11-01T18:37:31+00:00

The grace period used internally within tracepoint.c:release_probes()
uses call_rcu() to batch waiting for quiescence of old probe arrays,
rather than using the tracepoint_synchronize_unregister() which blocks
while waiting for quiescence.

With the introduction of faultable syscall tracepoints, this causes
use-after-free issues reproduced with syzkaller.

Fix this by using the appropriate call_rcu() or call_rcu_tasks_trace()
before invoking the rcu_free_old_probes callback. This can be chosen
using the tracepoint_is_faultable() API.

A similar issue exists in bpf use of call_rcu(). Fixing this is left to
a separate change.

Reported-by: syzbot+b390c8062d8387b6272a@syzkaller.appspotmail.com
Fixes: a363d27cdbc2 ("tracing: Allow system call tracepoints to handle page faults")
Tested-by: Jordan Rife 
Cc: Michael Jeanson 
Cc: Thomas Gleixner 
Cc: Masami Hiramatsu 
Cc: Peter Zijlstra 
Cc: Alexei Starovoitov 
Cc: Yonghong Song 
Cc: Paul E. McKenney 
Cc: Ingo Molnar 
Cc: Arnaldo Carvalho de Melo 
Cc: Mark Rutland 
Cc: Alexander Shishkin 
Cc: Namhyung Kim 
Cc: Andrii Nakryiko 
Cc: bpf@vger.kernel.org
Cc: Joel Fernandes 
Cc: Jordan Rife 
Cc: linux-trace-kernel@vger.kernel.org
Link: https://lore.kernel.org/20241031152056.744137-4-mathieu.desnoyers@efficios.com
Signed-off-by: Mathieu Desnoyers 
Signed-off-by: Steven Rostedt (Google)

tracing: Introduce tracepoint extended structure

2024-11-01T18:37:31+00:00

Shrink the struct tracepoint size from 80 bytes to 72 bytes on x86-64 by
moving the (typically NULL) regfunc/unregfunc pointers to an extended
structure.

Tested-by: Jordan Rife 
Cc: Michael Jeanson 
Cc: Thomas Gleixner 
Cc: Masami Hiramatsu 
Cc: Peter Zijlstra 
Cc: Alexei Starovoitov 
Cc: Yonghong Song 
Cc: Paul E. McKenney 
Cc: Ingo Molnar 
Cc: Arnaldo Carvalho de Melo 
Cc: Mark Rutland 
Cc: Alexander Shishkin 
Cc: Namhyung Kim 
Cc: Andrii Nakryiko 
Cc: bpf@vger.kernel.org
Cc: Joel Fernandes 
Cc: Jordan Rife 
Cc: linux-trace-kernel@vger.kernel.org
Link: https://lore.kernel.org/20241031152056.744137-2-mathieu.desnoyers@efficios.com
Signed-off-by: Mathieu Desnoyers 
Signed-off-by: Steven Rostedt (Google)

tracepoint: Remove SRCU protection

2024-10-09T01:17:39+00:00

With the removal of the trace_*_rcuidle() tracepoints, there is no reason
to protect tracepoints with SRCU. The reason the SRCU protection was
added, was because it can protect tracepoints when RCU is not "watching".
Now that tracepoints are only used when RCU is watching, remove the SRCU
protection. It just made things more complex and confusing anyway.

Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Joel Fernandes 
Link: https://lore.kernel.org/20241003184220.0dc21d35@gandalf.local.home
Acked-by: Peter Zijlstra (Intel) 
Signed-off-by: Steven Rostedt (Google)

tracepoints: Use new static branch API

2024-10-09T01:17:39+00:00

The old static key API is deprecated.  Switch to the new one.

Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Alice Ryhl 
Link: https://lore.kernel.org/7a08dae3c5eddb14b13864923c1b58ac1f4af83c.1728414936.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Steven Rostedt (Google)

tracepoint: Support iterating tracepoints in a loading module

2024-09-25T14:23:44+00:00

Add for_each_tracepoint_in_module() function to iterate tracepoints in
a module. This API is needed for handling tracepoints in a loading
module from tracepoint_module_notifier callback function.
This also update for_each_module_tracepoint() to pass the module to
callback function so that it can find module easily.

Link: https://lore.kernel.org/all/172397778740.286558.15781131277732977643.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google)