On Mon, Jun 22, 2026 at 09:07:41AM -0400, Steven Rostedt wrote: > From: Steven Rostedt <[email protected]> > > There have been complaints about trace_printk.h causing more build time > for being in kernel.h. Move it out of kernel.h and place it in the headers > and C files that use it. > > Link: > https://lore.kernel.org/all/CAHk-=wikcbevfjvxiy4o-oepdbjaoir5+tcagtl12c4u1tp...@mail.gmail.com/
Link is nice, but can you explain in the commit message what those complaints exactly are? There's enough opinions shared to make a nice summary. I even think it's important enough to become a Documentation rule. > Signed-off-by: Steven Rostedt <[email protected]> > --- > Changes since v1: https://patch.msgid.link/[email protected] > > - Just remove trace_printk.h and fix up all the places that need it. > > arch/powerpc/kvm/book3s_xics.c | 1 + > drivers/gpu/drm/i915/gt/intel_gtt.h | 1 + > drivers/gpu/drm/i915/i915_gem.h | 1 + > drivers/hwtracing/stm/dummy_stm.c | 4 ++++ > drivers/infiniband/hw/hfi1/trace_dbg.h | 1 + > drivers/usb/early/xhci-dbc.c | 1 + > fs/ext4/inline.c | 1 + > include/linux/ftrace.h | 2 ++ > include/linux/kernel.h | 1 - > include/linux/sunrpc/debug.h | 1 + > include/linux/trace_printk.h | 5 +++-- > kernel/trace/ring_buffer_benchmark.c | 1 + > samples/fprobe/fprobe_example.c | 1 + > samples/ftrace/ftrace-direct-too.c | 1 - > samples/trace_printk/trace-printk.c | 1 + > 15 files changed, 19 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_xics.c b/arch/powerpc/kvm/book3s_xics.c > index 74a44fa702b0..ef5eb596a56e 100644 > --- a/arch/powerpc/kvm/book3s_xics.c > +++ b/arch/powerpc/kvm/book3s_xics.c > @@ -26,6 +26,7 @@ > #if 1 > #define XICS_DBG(fmt...) do { } while (0) > #else > +#include <linux/trace_printk.h> > #define XICS_DBG(fmt...) trace_printk(fmt) > #endif > > diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h > b/drivers/gpu/drm/i915/gt/intel_gtt.h > index b54ee4f25af1..f6f223090760 100644 > --- a/drivers/gpu/drm/i915/gt/intel_gtt.h > +++ b/drivers/gpu/drm/i915/gt/intel_gtt.h > @@ -35,6 +35,7 @@ > #define I915_GFP_ALLOW_FAIL (GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN) > > #if IS_ENABLED(CONFIG_DRM_I915_TRACE_GTT) > +#include <linux/trace_printk.h> So, before it was included unconditionally, now it's included. It looks technically correct, but conceptually - I'm not sure. I'm not a developer of this driver, but ... here we need trace_printk.h if TRACE_GTT is enabled, in the next header TRACE_GEM needs it. To me it sounds like the whole driver simply needs trace_printk.h. > #define GTT_TRACE(...) trace_printk(__VA_ARGS__) > #else > #define GTT_TRACE(...) > diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h > index 1da8fb61c09e..f490052e8964 100644 > --- a/drivers/gpu/drm/i915/i915_gem.h > +++ b/drivers/gpu/drm/i915/i915_gem.h > @@ -117,6 +117,7 @@ int i915_gem_open(struct drm_i915_private *i915, struct > drm_file *file); > > #if IS_ENABLED(CONFIG_DRM_I915_TRACE_GEM) > #include <linux/trace_controls.h> > +#include <linux/trace_printk.h> > #define GEM_TRACE(...) trace_printk(__VA_ARGS__) > #define GEM_TRACE_ERR(...) do { > \ > pr_err(__VA_ARGS__); \ > diff --git a/drivers/hwtracing/stm/dummy_stm.c > b/drivers/hwtracing/stm/dummy_stm.c > index 38528ffdc0b3..784f9af7ccba 100644 > --- a/drivers/hwtracing/stm/dummy_stm.c > +++ b/drivers/hwtracing/stm/dummy_stm.c > @@ -14,6 +14,10 @@ > #include <linux/stm.h> > #include <uapi/linux/stm.h> > > +#ifdef DEBUG > +#include <linux/trace_printk.h> > +#endif > + Same here. The cost of adding the header in a particular C file is unmeasurable. But playing "#undef DEBUG #ifdef DEBUG" games looks weird. Imagine, the developer has this DEBUG enabled, then adds another debugging trace_pritnk() out of the DEBUG block, compiles his patch well, then sends to the user, who has DEBUG disabled; and now we hit the same problem as in the config-based case. Let's put it simple: dummy_stm just needs trace_printk.h. > static ssize_t notrace > dummy_stm_packet(struct stm_data *stm_data, unsigned int master, > unsigned int channel, unsigned int packet, unsigned int flags, > diff --git a/drivers/infiniband/hw/hfi1/trace_dbg.h > b/drivers/infiniband/hw/hfi1/trace_dbg.h > index 58304b91380f..30df5e246586 100644 > --- a/drivers/infiniband/hw/hfi1/trace_dbg.h > +++ b/drivers/infiniband/hw/hfi1/trace_dbg.h > @@ -103,6 +103,7 @@ __hfi1_trace_def(IOCTL); > */ > > #ifdef HFI1_EARLY_DBG > +#include <linux/trace_printk.h> > #define hfi1_dbg_early(fmt, ...) \ > trace_printk(fmt, ##__VA_ARGS__) > #else > diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c > index 41118bba9197..955c73bd601f 100644 > --- a/drivers/usb/early/xhci-dbc.c > +++ b/drivers/usb/early/xhci-dbc.c > @@ -30,6 +30,7 @@ static struct xdbc_state xdbc; > static bool early_console_keep; > > #ifdef XDBC_TRACE > +#include <linux/trace_printk.h> > #define xdbc_trace trace_printk > #else > static inline void xdbc_trace(const char *fmt, ...) { } > diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c > index 8045e4ff270c..0eff4a0c6a6c 100644 > --- a/fs/ext4/inline.c > +++ b/fs/ext4/inline.c > @@ -934,6 +934,7 @@ static int ext4_da_convert_inline_data_to_extent(struct > address_space *mapping, > } > > #ifdef INLINE_DIR_DEBUG > +#include <linux/trace_printk.h> > void ext4_show_inline_dir(struct inode *dir, struct buffer_head *bh, > void *inline_start, int inline_size) > { > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 02bc5027523a..b5336a81e619 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -8,6 +8,8 @@ > #define _LINUX_FTRACE_H > > #include <linux/trace_recursion.h> > +#include <linux/trace_controls.h> > +#include <linux/trace_printk.h> > #include <linux/trace_clock.h> > #include <linux/jump_label.h> > #include <linux/kallsyms.h> > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index e5570a16cbb1..e87a40fbd152 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -31,7 +31,6 @@ > #include <linux/build_bug.h> > #include <linux/sprintf.h> > #include <linux/static_call_types.h> > -#include <linux/trace_printk.h> > #include <linux/util_macros.h> > #include <linux/wordpart.h> > > diff --git a/include/linux/sunrpc/debug.h b/include/linux/sunrpc/debug.h > index ab61bed2f7af..7524f5d82fba 100644 > --- a/include/linux/sunrpc/debug.h > +++ b/include/linux/sunrpc/debug.h > @@ -29,6 +29,7 @@ extern unsigned int nlm_debug; > # define ifdebug(fac) if (unlikely(rpc_debug & RPCDBG_##fac)) > > # if IS_ENABLED(CONFIG_SUNRPC_DEBUG_TRACE) > +# include <linux/trace_printk.h> > # define __sunrpc_printk(fmt, ...) trace_printk(fmt, ##__VA_ARGS__) > # else > # define __sunrpc_printk(fmt, ...) printk(KERN_DEFAULT fmt, ##__VA_ARGS__) > diff --git a/include/linux/trace_printk.h b/include/linux/trace_printk.h > index a488ea9e9f85..74ce4f8995c4 100644 > --- a/include/linux/trace_printk.h > +++ b/include/linux/trace_printk.h > @@ -1,11 +1,12 @@ > /* SPDX-License-Identifier: GPL-2.0 */ > #ifndef _LINUX_TRACE_PRINTK_H > #define _LINUX_TRACE_PRINTK_H > +#if !defined(__ASSEMBLY__) && !defined(__GENKSYMS__) && !defined(BUILD_VDSO) > > -#include <linux/compiler_attributes.h> > #include <linux/instruction_pointer.h> > #include <linux/stddef.h> > #include <linux/stringify.h> > +#include <linux/stdarg.h> > > #ifdef CONFIG_TRACING > static inline __printf(1, 2) > @@ -147,5 +148,5 @@ ftrace_vprintk(const char *fmt, va_list ap) > return 0; > } > #endif /* CONFIG_TRACING */ > - > +#endif /* !defined(__ASSEMBLY__) && !defined(__GENKSYMS__) && > !defined(BUILD_VDSO) */ > #endif > diff --git a/kernel/trace/ring_buffer_benchmark.c > b/kernel/trace/ring_buffer_benchmark.c > index 593e3b59e42e..2bb25caebb75 100644 > --- a/kernel/trace/ring_buffer_benchmark.c > +++ b/kernel/trace/ring_buffer_benchmark.c > @@ -5,6 +5,7 @@ > * Copyright (C) 2009 Steven Rostedt <[email protected]> > */ > #include <linux/ring_buffer.h> > +#include <linux/trace_printk.h> > #include <linux/completion.h> > #include <linux/kthread.h> > #include <uapi/linux/sched/types.h> > diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c > index bfe98ce826f3..de81b9b4ca7d 100644 > --- a/samples/fprobe/fprobe_example.c > +++ b/samples/fprobe/fprobe_example.c > @@ -12,6 +12,7 @@ > > #define pr_fmt(fmt) "%s: " fmt, __func__ > > +#include <linux/trace_printk.h> > #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/fprobe.h> > diff --git a/samples/ftrace/ftrace-direct-too.c > b/samples/ftrace/ftrace-direct-too.c > index bf2411aa6fd7..159190f4103f 100644 > --- a/samples/ftrace/ftrace-direct-too.c > +++ b/samples/ftrace/ftrace-direct-too.c > @@ -1,6 +1,5 @@ > // SPDX-License-Identifier: GPL-2.0-only > #include <linux/module.h> > - > #include <linux/mm.h> /* for handle_mm_fault() */ > #include <linux/ftrace.h> > #if !defined(CONFIG_ARM64) && !defined(CONFIG_PPC32) > diff --git a/samples/trace_printk/trace-printk.c > b/samples/trace_printk/trace-printk.c > index cfc159580263..ff37aeb8523e 100644 > --- a/samples/trace_printk/trace-printk.c > +++ b/samples/trace_printk/trace-printk.c > @@ -1,4 +1,5 @@ > // SPDX-License-Identifier: GPL-2.0-only > +#include <linux/trace_printk.h> > #include <linux/module.h> > #include <linux/kthread.h> > #include <linux/irq_work.h> > -- > 2.53.0 >
