[PATCH 00/12] [GIT PULL] tracing: fixes

[PATCH 00/12] [GIT PULL] tracing: fixes

[Steven Rostedt]

Ingo,

This patch set contains all fixes. Some of the fixes are to get
rid of warnings, but I think getting rid of warnings is a good thing
during a merge window.

What's different about this and my last pull request:

1) I removed the two patches that were not bug fixes and put them
   in my queue for 2.6.41/3.1/2.8.1

2) I added two patches, one that was a bug fix that caused a
   triple fault when PROVE_RCU was set, and the other that caused
   problems with truncating 64bit words in the trace events.

3) I pulled out Masami's kprobe stack trace fix because it failed
   on other archs. My last push request, I did compile test other
   archs, but I only used the default config. This time, I enabled
   tracing as well (doing it both with and without tracing enabled)
   and when tracing was enabled, I detected the problem with the lack
   of save_stack_trace_regs() in other archs.

I tested this on x86_64 and x86_32 as well as compiled tested for
the following archs, with and without tracing enabled:

 alpha, arm, blackfin, ia64, parsic, ppc, ppc64, sparc

The following had failures for other reason (failed without this
patch set):

  cris, cris32, m68k, mips64, mips32, parsic64, sh, xtensa, uml.


Please pull the latest tip/perf/urgent tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/perf/urgent


Jiri Olsa (1):
      jump_label: Check entries limit in __jump_label_update

Rabin Vincent (1):
      ftrace/recordmcount: Avoid STT_FUNC symbols as base on ARM

Rakib Mullick (1):
      x86/ftrace: Fix compiler warning in ftrace.c

Steven Rostedt (7):
      maccess,probe_kernel: Make write/read src const void *
      scripts/tags.sh: Fix ctags for DEFINE_EVENT()
      scripts/tags.sh: Add magic for trace-events for etags too
      ftrace: Have ftrace_startup() return failure code
      tracing: Have event with function tracer check error return
      ftrace: Set ops->flag to enabled even on static function tracing
      ftrace: Add internal recursive checks

liubo (2):
      tracing: Add __print_symbolic_u64 to avoid warnings on 32bit machine
      tracing: Update btrfs's tracepoints to use u64 interface

----
 arch/blackfin/mm/maccess.c   |    4 ++--
 arch/s390/mm/maccess.c       |    4 ++--
 arch/x86/kernel/ftrace.c     |   12 ++++++------
 include/linux/ftrace_event.h |   12 ++++++++++++
 include/linux/sched.h        |    2 +-
 include/linux/uaccess.h      |    8 ++++----
 include/trace/events/btrfs.h |    4 ++--
 include/trace/ftrace.h       |   13 +++++++++++++
 kernel/jump_label.c          |   18 +++++++++++++-----
 kernel/trace/ftrace.c        |   31 ++++++++++++++++++++++++-------
 kernel/trace/ring_buffer.c   |   10 +++++-----
 kernel/trace/trace.h         |   15 +++++++++++++++
 kernel/trace/trace_events.c  |    7 ++++++-
 kernel/trace/trace_output.c  |   27 +++++++++++++++++++++++++++
 mm/maccess.c                 |    8 ++++----
 scripts/recordmcount.h       |    8 ++++++++
 scripts/tags.sh              |    6 ++++--
 17 files changed, 148 insertions(+), 41 deletions(-)

[PATCH 01/12] maccess,probe_kernel: Make write/read src const void *

[Steven Rostedt]

[-- Attachment #1: 0001-maccess-probe_kernel-Make-write-read-src-const-void.patch --]
[-- Type: text/plain, Size: 4621 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The functions probe_kernel_write() and probe_kernel_read() do not modify
the src pointer. Allow const pointers to be passed in without the need
of a typecast.

Acked-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1305824936.1465.4.camel@gandalf.stny.rr.com
---
 arch/blackfin/mm/maccess.c |    4 ++--
 arch/s390/mm/maccess.c     |    4 ++--
 include/linux/uaccess.h    |    8 ++++----
 mm/maccess.c               |    8 ++++----
 4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/blackfin/mm/maccess.c b/arch/blackfin/mm/maccess.c
index b71cebc..e253211 100644
--- a/arch/blackfin/mm/maccess.c
+++ b/arch/blackfin/mm/maccess.c
@@ -16,7 +16,7 @@ static int validate_memory_access_address(unsigned long addr, int size)
 	return bfin_mem_access_type(addr, size);
 }
 
-long probe_kernel_read(void *dst, void *src, size_t size)
+long probe_kernel_read(void *dst, const void *src, size_t size)
 {
 	unsigned long lsrc = (unsigned long)src;
 	int mem_type;
@@ -55,7 +55,7 @@ long probe_kernel_read(void *dst, void *src, size_t size)
 	return -EFAULT;
 }
 
-long probe_kernel_write(void *dst, void *src, size_t size)
+long probe_kernel_write(void *dst, const void *src, size_t size)
 {
 	unsigned long ldst = (unsigned long)dst;
 	int mem_type;
diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c
index 71a4b0d..51e5cd9 100644
--- a/arch/s390/mm/maccess.c
+++ b/arch/s390/mm/maccess.c
@@ -19,7 +19,7 @@
  * using the stura instruction.
  * Returns the number of bytes copied or -EFAULT.
  */
-static long probe_kernel_write_odd(void *dst, void *src, size_t size)
+static long probe_kernel_write_odd(void *dst, const void *src, size_t size)
 {
 	unsigned long count, aligned;
 	int offset, mask;
@@ -45,7 +45,7 @@ static long probe_kernel_write_odd(void *dst, void *src, size_t size)
 	return rc ? rc : count;
 }
 
-long probe_kernel_write(void *dst, void *src, size_t size)
+long probe_kernel_write(void *dst, const void *src, size_t size)
 {
 	long copied = 0;
 
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index d512d98..5ca0951 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -93,8 +93,8 @@ static inline unsigned long __copy_from_user_nocache(void *to,
  * Safely read from address @src to the buffer at @dst.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-extern long probe_kernel_read(void *dst, void *src, size_t size);
-extern long __probe_kernel_read(void *dst, void *src, size_t size);
+extern long probe_kernel_read(void *dst, const void *src, size_t size);
+extern long __probe_kernel_read(void *dst, const void *src, size_t size);
 
 /*
  * probe_kernel_write(): safely attempt to write to a location
@@ -105,7 +105,7 @@ extern long __probe_kernel_read(void *dst, void *src, size_t size);
  * Safely write to address @dst from the buffer at @src.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-extern long notrace probe_kernel_write(void *dst, void *src, size_t size);
-extern long notrace __probe_kernel_write(void *dst, void *src, size_t size);
+extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
+extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
 
 #endif		/* __LINUX_UACCESS_H__ */
diff --git a/mm/maccess.c b/mm/maccess.c
index e2b6f56..4cee182 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -15,10 +15,10 @@
  * happens, handle that and return -EFAULT.
  */
 
-long __weak probe_kernel_read(void *dst, void *src, size_t size)
+long __weak probe_kernel_read(void *dst, const void *src, size_t size)
     __attribute__((alias("__probe_kernel_read")));
 
-long __probe_kernel_read(void *dst, void *src, size_t size)
+long __probe_kernel_read(void *dst, const void *src, size_t size)
 {
 	long ret;
 	mm_segment_t old_fs = get_fs();
@@ -43,10 +43,10 @@ EXPORT_SYMBOL_GPL(probe_kernel_read);
  * Safely write to address @dst from the buffer at @src.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-long __weak probe_kernel_write(void *dst, void *src, size_t size)
+long __weak probe_kernel_write(void *dst, const void *src, size_t size)
     __attribute__((alias("__probe_kernel_write")));
 
-long __probe_kernel_write(void *dst, void *src, size_t size)
+long __probe_kernel_write(void *dst, const void *src, size_t size)
 {
 	long ret;
 	mm_segment_t old_fs = get_fs();
-- 
1.7.4.4

[PATCH 02/12] x86/ftrace: Fix compiler warning in ftrace.c

[Steven Rostedt]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: 0002-x86-ftrace-Fix-compiler-warning-in-ftrace.c.patch --]
[-- Type: text/plain, Size: 2865 bytes --]

From: Rakib Mullick <rakib.mullick@gmail.com>

 Due to commit dc326fca2b64 (x86, cpu: Clean up and unify the NOP selection infrastructure), we get the following warning:

arch/x86/kernel/ftrace.c: In function ‘ftrace_make_nop’:
arch/x86/kernel/ftrace.c:308:6: warning: assignment discards qualifiers from pointer target type
arch/x86/kernel/ftrace.c: In function ‘ftrace_make_call’:
arch/x86/kernel/ftrace.c:318:6: warning: assignment discards qualifiers from pointer target type

ftrace_nop_replace() now returns const unsigned char *, so change its associated function/variable to its compatible type to keep compiler clam.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Link: http://lkml.kernel.org/r/1305221620.7986.4.camel@localhost.localdomain

[ updated for change of const void *src in probe_kernel_write() ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/kernel/ftrace.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 0ba15a6..c9a281f 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -123,7 +123,7 @@ static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 static atomic_t nmi_running = ATOMIC_INIT(0);
 static int mod_code_status;		/* holds return value of text write */
 static void *mod_code_ip;		/* holds the IP to write to */
-static void *mod_code_newcode;		/* holds the text to write to the IP */
+static const void *mod_code_newcode;	/* holds the text to write to the IP */
 
 static unsigned nmi_wait_count;
 static atomic_t nmi_update_count = ATOMIC_INIT(0);
@@ -225,7 +225,7 @@ within(unsigned long addr, unsigned long start, unsigned long end)
 }
 
 static int
-do_ftrace_mod_code(unsigned long ip, void *new_code)
+do_ftrace_mod_code(unsigned long ip, const void *new_code)
 {
 	/*
 	 * On x86_64, kernel text mappings are mapped read-only with
@@ -266,8 +266,8 @@ static const unsigned char *ftrace_nop_replace(void)
 }
 
 static int
-ftrace_modify_code(unsigned long ip, unsigned char *old_code,
-		   unsigned char *new_code)
+ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
+		   unsigned const char *new_code)
 {
 	unsigned char replaced[MCOUNT_INSN_SIZE];
 
@@ -301,7 +301,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 int ftrace_make_nop(struct module *mod,
 		    struct dyn_ftrace *rec, unsigned long addr)
 {
-	unsigned char *new, *old;
+	unsigned const char *new, *old;
 	unsigned long ip = rec->ip;
 
 	old = ftrace_call_replace(ip, addr);
@@ -312,7 +312,7 @@ int ftrace_make_nop(struct module *mod,
 
 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
-	unsigned char *new, *old;
+	unsigned const char *new, *old;
 	unsigned long ip = rec->ip;
 
 	old = ftrace_nop_replace();
-- 
1.7.4.4

[PATCH 03/12] scripts/tags.sh: Fix ctags for DEFINE_EVENT()

[Steven Rostedt]

[-- Attachment #1: 0003-scripts-tags.sh-Fix-ctags-for-DEFINE_EVENT.patch --]
[-- Type: text/plain, Size: 1043 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The regex to handle DEFINE_EVENT() should not be the same as
the TRACE_EVENT() as the first parameter in DEFINE_EVENT is the
template name, not the event name. We need the second parameter
as that is what the trace_... will use.

Tested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 scripts/tags.sh |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/scripts/tags.sh b/scripts/tags.sh
index bd6185d..33b53ca 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -132,7 +132,7 @@ exuberant()
 	--regex-asm='/^ENTRY\(([^)]*)\).*/\1/'                  \
 	--regex-c='/^SYSCALL_DEFINE[[:digit:]]?\(([^,)]*).*/sys_\1/' \
 	--regex-c++='/^TRACE_EVENT\(([^,)]*).*/trace_\1/'		\
-	--regex-c++='/^DEFINE_EVENT\(([^,)]*).*/trace_\1/'
+	--regex-c++='/^DEFINE_EVENT\([^,)]*, *([^,)]*).*/trace_\1/'
 
 	all_kconfigs | xargs $1 -a                              \
 	--langdef=kconfig --language-force=kconfig              \
-- 
1.7.4.4

[PATCH 04/12] scripts/tags.sh: Add magic for trace-events for etags too

[Steven Rostedt]

[-- Attachment #1: 0004-scripts-tags.sh-Add-magic-for-trace-events-for-etags.patch --]
[-- Type: text/plain, Size: 1206 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Seems that Peter Zijlstra treats us emacs users as second class
citizens and the commit:

 commit 15664125f7cadcb6d725cb2d9b90f9715397848d
 Author: Peter Zijlstra <peterz@infradead.org>
 scripts/tags.sh: Add magic for trace-events

only updated ctags (for vim) and did not do the work to let us
lowly emacs users benefit from such a change.

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 scripts/tags.sh |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/scripts/tags.sh b/scripts/tags.sh
index 33b53ca..75c5d24 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -152,7 +152,9 @@ emacs()
 {
 	all_sources | xargs $1 -a                               \
 	--regex='/^ENTRY(\([^)]*\)).*/\1/'                      \
-	--regex='/^SYSCALL_DEFINE[0-9]?(\([^,)]*\).*/sys_\1/'
+	--regex='/^SYSCALL_DEFINE[0-9]?(\([^,)]*\).*/sys_\1/'   \
+	--regex='/^TRACE_EVENT(\([^,)]*\).*/trace_\1/'		\
+	--regex='/^DEFINE_EVENT([^,)]*, *\([^,)]*\).*/trace_\1/'
 
 	all_kconfigs | xargs $1 -a                              \
 	--regex='/^[ \t]*\(\(menu\)*config\)[ \t]+\([a-zA-Z0-9_]+\)/\3/'
-- 
1.7.4.4

Re: [PATCH 04/12] scripts/tags.sh: Add magic for trace-events for etags too

[Peter Zijlstra]

On Thu, 2011-05-26 at 11:25 -0400, Steven Rostedt wrote:

> Seems that Peter Zijlstra treats us emacs users as second class
> citizens and the commit:

Yeah, I actually use Linux as my OS ;-)

/me runs

anyway, yeah, I completely missed that there were two series of regexes
in there.

[PATCH 05/12] ftrace/recordmcount: Avoid STT_FUNC symbols as base on ARM

[Steven Rostedt]

[-- Attachment #1: 0005-ftrace-recordmcount-Avoid-STT_FUNC-symbols-as-base-o.patch --]
[-- Type: text/plain, Size: 2157 bytes --]

From: Rabin Vincent <rabin@rab.in>

While find_secsym_ndx often finds the unamed local STT_SECTION, if a
section has only one function in it, the ARM toolchain generates the
STT_FUNC symbol before the STT_SECTION, and recordmcount finds this
instead.

This is problematic on ARM because in ARM ELFs, "if a [STT_FUNC] symbol
addresses a Thumb instruction, its value is the address of the
instruction with bit zero set (in a relocatable object, the section
offset with bit zero set)".  This leads to incorrect mcount addresses
being recorded.

Fix this by not using STT_FUNC symbols as the base on ARM.

Signed-off-by: Rabin Vincent <rabin@rab.in>
Link: http://lkml.kernel.org/r/1305134631-31617-1-git-send-email-rabin@rab.in
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 scripts/recordmcount.h |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 4be6036..f40a6af6 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -43,6 +43,7 @@
 #undef ELF_R_INFO
 #undef Elf_r_info
 #undef ELF_ST_BIND
+#undef ELF_ST_TYPE
 #undef fn_ELF_R_SYM
 #undef fn_ELF_R_INFO
 #undef uint_t
@@ -76,6 +77,7 @@
 # define ELF_R_INFO		ELF64_R_INFO
 # define Elf_r_info		Elf64_r_info
 # define ELF_ST_BIND		ELF64_ST_BIND
+# define ELF_ST_TYPE		ELF64_ST_TYPE
 # define fn_ELF_R_SYM		fn_ELF64_R_SYM
 # define fn_ELF_R_INFO		fn_ELF64_R_INFO
 # define uint_t			uint64_t
@@ -108,6 +110,7 @@
 # define ELF_R_INFO		ELF32_R_INFO
 # define Elf_r_info		Elf32_r_info
 # define ELF_ST_BIND		ELF32_ST_BIND
+# define ELF_ST_TYPE		ELF32_ST_TYPE
 # define fn_ELF_R_SYM		fn_ELF32_R_SYM
 # define fn_ELF_R_INFO		fn_ELF32_R_INFO
 # define uint_t			uint32_t
@@ -427,6 +430,11 @@ static unsigned find_secsym_ndx(unsigned const txtndx,
 		if (txtndx == w2(symp->st_shndx)
 			/* avoid STB_WEAK */
 		    && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
+			/* function symbols on ARM have quirks, avoid them */
+			if (w2(ehdr->e_machine) == EM_ARM
+			    && ELF_ST_TYPE(symp->st_info) == STT_FUNC)
+				continue;
+
 			*recvalp = _w(symp->st_value);
 			return symp - sym0;
 		}
-- 
1.7.4.4

[PATCH 06/12] jump_label: Check entries limit in __jump_label_update

[Steven Rostedt]

[-- Attachment #1: 0006-jump_label-Check-entries-limit-in-__jump_label_updat.patch --]
[-- Type: text/plain, Size: 2557 bytes --]

From: Jiri Olsa <jolsa@redhat.com>

When iterating the jump_label entries array (core or modules),
the __jump_label_update function peeks over the last entry.

The reason is that the end of the for loop depends on the key
value of the processed entry. Thus when going through the
last array entry, we will touch the memory behind the array
limit.

This bug probably will never be triggered, since most likely the
memory behind the jump_label entries will be accesable and the
entry->key will be different than the expected value.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Jason Baron <jbaron@redhat.com>
Link: http://lkml.kernel.org/r/20110510104346.GC1899@jolsa.brq.redhat.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/jump_label.c |   18 +++++++++++++-----
 1 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 74d1c09..fa27e75 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -105,9 +105,12 @@ static int __jump_label_text_reserved(struct jump_entry *iter_start,
 }
 
 static void __jump_label_update(struct jump_label_key *key,
-		struct jump_entry *entry, int enable)
+				struct jump_entry *entry,
+				struct jump_entry *stop, int enable)
 {
-	for (; entry->key == (jump_label_t)(unsigned long)key; entry++) {
+	for (; (entry < stop) &&
+	      (entry->key == (jump_label_t)(unsigned long)key);
+	      entry++) {
 		/*
 		 * entry->code set to 0 invalidates module init text sections
 		 * kernel_text_address() verifies we are not in core kernel
@@ -181,7 +184,11 @@ static void __jump_label_mod_update(struct jump_label_key *key, int enable)
 	struct jump_label_mod *mod = key->next;
 
 	while (mod) {
-		__jump_label_update(key, mod->entries, enable);
+		struct module *m = mod->mod;
+
+		__jump_label_update(key, mod->entries,
+				    m->jump_entries + m->num_jump_entries,
+				    enable);
 		mod = mod->next;
 	}
 }
@@ -245,7 +252,8 @@ static int jump_label_add_module(struct module *mod)
 		key->next = jlm;
 
 		if (jump_label_enabled(key))
-			__jump_label_update(key, iter, JUMP_LABEL_ENABLE);
+			__jump_label_update(key, iter, iter_stop,
+					    JUMP_LABEL_ENABLE);
 	}
 
 	return 0;
@@ -371,7 +379,7 @@ static void jump_label_update(struct jump_label_key *key, int enable)
 
 	/* if there are no users, entry can be NULL */
 	if (entry)
-		__jump_label_update(key, entry, enable);
+		__jump_label_update(key, entry, __stop___jump_table, enable);
 
 #ifdef CONFIG_MODULES
 	__jump_label_mod_update(key, enable);
-- 
1.7.4.4

[PATCH 07/12] ftrace: Have ftrace_startup() return failure code

[Steven Rostedt]

[-- Attachment #1: 0007-ftrace-Have-ftrace_startup-return-failure-code.patch --]
[-- Type: text/plain, Size: 2522 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The register_ftrace_function() returns an error code on failure
except if the call to ftrace_startup() fails. Add a error return to
ftrace_startup() if it fails to start, allowing register_ftrace_funtion()
to return a proper error value.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d017c2c..bebbc95 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1638,12 +1638,12 @@ static void ftrace_startup_enable(int command)
 	ftrace_run_update_code(command);
 }
 
-static void ftrace_startup(struct ftrace_ops *ops, int command)
+static int ftrace_startup(struct ftrace_ops *ops, int command)
 {
 	bool hash_enable = true;
 
 	if (unlikely(ftrace_disabled))
-		return;
+		return -ENODEV;
 
 	ftrace_start_up++;
 	command |= FTRACE_ENABLE_CALLS;
@@ -1662,6 +1662,8 @@ static void ftrace_startup(struct ftrace_ops *ops, int command)
 		ftrace_hash_rec_enable(ops, 1);
 
 	ftrace_startup_enable(command);
+
+	return 0;
 }
 
 static void ftrace_shutdown(struct ftrace_ops *ops, int command)
@@ -2501,7 +2503,7 @@ static void __enable_ftrace_function_probe(void)
 
 	ret = __register_ftrace_function(&trace_probe_ops);
 	if (!ret)
-		ftrace_startup(&trace_probe_ops, 0);
+		ret = ftrace_startup(&trace_probe_ops, 0);
 
 	ftrace_probe_registered = 1;
 }
@@ -3466,7 +3468,7 @@ device_initcall(ftrace_nodyn_init);
 static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
 static inline void ftrace_startup_enable(int command) { }
 /* Keep as macros so we do not need to define the commands */
-# define ftrace_startup(ops, command)	do { } while (0)
+# define ftrace_startup(ops, command)	({0;})
 # define ftrace_shutdown(ops, command)	do { } while (0)
 # define ftrace_startup_sysctl()	do { } while (0)
 # define ftrace_shutdown_sysctl()	do { } while (0)
@@ -3799,7 +3801,7 @@ int register_ftrace_function(struct ftrace_ops *ops)
 
 	ret = __register_ftrace_function(ops);
 	if (!ret)
-		ftrace_startup(ops, 0);
+		ret = ftrace_startup(ops, 0);
 
 
  out_unlock:
@@ -4045,7 +4047,7 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 	ftrace_graph_return = retfunc;
 	ftrace_graph_entry = entryfunc;
 
-	ftrace_startup(&global_ops, FTRACE_START_FUNC_RET);
+	ret = ftrace_startup(&global_ops, FTRACE_START_FUNC_RET);
 
 out:
 	mutex_unlock(&ftrace_lock);
-- 
1.7.4.4

[PATCH 08/12] tracing: Have event with function tracer check error return

[Steven Rostedt]

[-- Attachment #1: 0008-tracing-Have-event-with-function-tracer-check-error-.patch --]
[-- Type: text/plain, Size: 1046 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The self tests for event tracer does not check if the function
tracing was successfully activated. It needs to before it continues
the tests, otherwise the wrong errors may be reported.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_events.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 2fe1103..686ec39 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1657,7 +1657,12 @@ static struct ftrace_ops trace_ops __initdata  =
 
 static __init void event_trace_self_test_with_function(void)
 {
-	register_ftrace_function(&trace_ops);
+	int ret;
+	ret = register_ftrace_function(&trace_ops);
+	if (WARN_ON(ret < 0)) {
+		pr_info("Failed to enable function tracer for event tests\n");
+		return;
+	}
 	pr_info("Running tests again, along with the function tracer\n");
 	event_trace_self_tests();
 	unregister_ftrace_function(&trace_ops);
-- 
1.7.4.4

[PATCH 09/12] ftrace: Set ops->flag to enabled even on static function tracing

[Steven Rostedt]

[-- Attachment #1: 0009-ftrace-Set-ops-flag-to-enabled-even-on-static-functi.patch --]
[-- Type: text/plain, Size: 1062 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

When dynamic ftrace is not configured, the ops->flags still needs
to have its FTRACE_OPS_FL_ENABLED bit set in ftrace_startup().

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index bebbc95..25949b3 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3468,7 +3468,11 @@ device_initcall(ftrace_nodyn_init);
 static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
 static inline void ftrace_startup_enable(int command) { }
 /* Keep as macros so we do not need to define the commands */
-# define ftrace_startup(ops, command)	({0;})
+# define ftrace_startup(ops, command)			\
+	({						\
+		(ops)->flags |= FTRACE_OPS_FL_ENABLED;	\
+		0;					\
+	})
 # define ftrace_shutdown(ops, command)	do { } while (0)
 # define ftrace_startup_sysctl()	do { } while (0)
 # define ftrace_shutdown_sysctl()	do { } while (0)
-- 
1.7.4.4

[PATCH 10/12] tracing: Add __print_symbolic_u64 to avoid warnings on 32bit machine

[Steven Rostedt]

[-- Attachment #1: 0010-tracing-Add-__print_symbolic_u64-to-avoid-warnings-o.patch --]
[-- Type: text/plain, Size: 3304 bytes --]

From: liubo <liubo2009@cn.fujitsu.com>

Filesystem, like Btrfs, has some "ULL" macros, and when these macros are passed
to tracepoints'__print_symbolic(), there will be 64->32 truncate WARNINGS during
compiling on 32bit box.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/4DACE6E0.7000507@cn.fujitsu.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ftrace_event.h |   12 ++++++++++++
 include/trace/ftrace.h       |   13 +++++++++++++
 kernel/trace/trace_output.c  |   27 +++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 0 deletions(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index b5a550a..59d3ef1 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -16,6 +16,11 @@ struct trace_print_flags {
 	const char		*name;
 };
 
+struct trace_print_flags_u64 {
+	unsigned long long	mask;
+	const char		*name;
+};
+
 const char *ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
 				   unsigned long flags,
 				   const struct trace_print_flags *flag_array);
@@ -23,6 +28,13 @@ const char *ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
 const char *ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
 				     const struct trace_print_flags *symbol_array);
 
+#if BITS_PER_LONG == 32
+const char *ftrace_print_symbols_seq_u64(struct trace_seq *p,
+					 unsigned long long val,
+					 const struct trace_print_flags_u64
+								 *symbol_array);
+#endif
+
 const char *ftrace_print_hex_seq(struct trace_seq *p,
 				 const unsigned char *buf, int len);
 
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 3e68366..533c49f 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -205,6 +205,19 @@
 		ftrace_print_symbols_seq(p, value, symbols);		\
 	})
 
+#undef __print_symbolic_u64
+#if BITS_PER_LONG == 32
+#define __print_symbolic_u64(value, symbol_array...)			\
+	({								\
+		static const struct trace_print_flags_u64 symbols[] =	\
+			{ symbol_array, { -1, NULL } };			\
+		ftrace_print_symbols_seq_u64(p, value, symbols);	\
+	})
+#else
+#define __print_symbolic_u64(value, symbol_array...)			\
+			__print_symbolic(value, symbol_array)
+#endif
+
 #undef __print_hex
 #define __print_hex(buf, buf_len) ftrace_print_hex_seq(p, buf, buf_len)
 
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index cf535cc..e37de49 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -353,6 +353,33 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
 }
 EXPORT_SYMBOL(ftrace_print_symbols_seq);
 
+#if BITS_PER_LONG == 32
+const char *
+ftrace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val,
+			 const struct trace_print_flags_u64 *symbol_array)
+{
+	int i;
+	const char *ret = p->buffer + p->len;
+
+	for (i = 0;  symbol_array[i].name; i++) {
+
+		if (val != symbol_array[i].mask)
+			continue;
+
+		trace_seq_puts(p, symbol_array[i].name);
+		break;
+	}
+
+	if (!p->len)
+		trace_seq_printf(p, "0x%llx", val);
+
+	trace_seq_putc(p, 0);
+
+	return ret;
+}
+EXPORT_SYMBOL(ftrace_print_symbols_seq_u64);
+#endif
+
 const char *
 ftrace_print_hex_seq(struct trace_seq *p, const unsigned char *buf, int buf_len)
 {
-- 
1.7.4.4

[PATCH 11/12] tracing: Update btrfss tracepoints to use u64 interface

[Steven Rostedt]

[-- Attachment #1: 0011-tracing-Update-btrfs-s-tracepoints-to-use-u64-interf.patch --]
[-- Type: text/plain, Size: 1207 bytes --]

From: liubo <liubo2009@cn.fujitsu.com>

To avoid 64->32 truncating WARNING, update btrfs's tracepoints.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/4DACE6E3.8080200@cn.fujitsu.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/trace/events/btrfs.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
index f445cff..4114129 100644
--- a/include/trace/events/btrfs.h
+++ b/include/trace/events/btrfs.h
@@ -28,7 +28,7 @@ struct extent_buffer;
 		{ BTRFS_SHARED_DATA_REF_KEY, 	"SHARED_DATA_REF" })
 
 #define __show_root_type(obj)						\
-	__print_symbolic(obj,						\
+	__print_symbolic_u64(obj,					\
 		{ BTRFS_ROOT_TREE_OBJECTID, 	"ROOT_TREE"	},	\
 		{ BTRFS_EXTENT_TREE_OBJECTID, 	"EXTENT_TREE"	},	\
 		{ BTRFS_CHUNK_TREE_OBJECTID, 	"CHUNK_TREE"	},	\
@@ -125,7 +125,7 @@ DEFINE_EVENT(btrfs__inode, btrfs_inode_evict,
 );
 
 #define __show_map_type(type)						\
-	__print_symbolic(type,						\
+	__print_symbolic_u64(type,					\
 		{ EXTENT_MAP_LAST_BYTE, "LAST_BYTE" 	},		\
 		{ EXTENT_MAP_HOLE, 	"HOLE" 		},		\
 		{ EXTENT_MAP_INLINE, 	"INLINE" 	},		\
-- 
1.7.4.4

[PATCH 12/12] ftrace: Add internal recursive checks

[Steven Rostedt]

[-- Attachment #1: 0012-ftrace-Add-internal-recursive-checks.patch --]
[-- Type: text/plain, Size: 6305 bytes --]

From: Steven Rostedt <rostedt@goodmis.org>

Witold reported a reboot caused by the selftests of the dynamic function
tracer. He sent me a config and I used ktest to do a config_bisect on it
(as my config did not cause the crash). It pointed out that the problem
config was CONFIG_PROVE_RCU.

What happened was that if multiple callbacks are attached to the
function tracer, we iterate a list of callbacks. Because the list is
managed by synchronize_sched() and preempt_disable, the access to the
pointers uses rcu_dereference_raw().

When PROVE_RCU is enabled, the rcu_dereference_raw() calls some
debugging functions, which happen to be traced. The tracing of the debug
function would then call rcu_dereference_raw() which would then call the
debug function and then... well you get the idea.

I first wrote two different patches to solve this bug.

1) add a __rcu_dereference_raw() that would not do any checks.
2) add notrace to the offending debug functions.

Both of these patches worked.

Talking with Paul McKenney on IRC, he suggested to add recursion
detection instead. This seemed to be a better solution, so I decided to
implement it. As the task_struct already has a trace_recursion to detect
recursion in the ring buffer, and that has a very small number it
allows, I decided to use that same variable to add flags that can detect
the recursion inside the infrastructure of the function tracer.

I plan to change it so that the task struct bit can be checked in
mcount, but as that requires changes to all archs, I will hold that off
to the next merge window.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1306348063.1465.116.camel@gandalf.stny.rr.com
Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/sched.h      |    2 +-
 kernel/trace/ftrace.c      |   13 ++++++++++++-
 kernel/trace/ring_buffer.c |   10 +++++-----
 kernel/trace/trace.h       |   15 +++++++++++++++
 4 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d8b2d0b..7b78d9c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1513,7 +1513,7 @@ struct task_struct {
 #ifdef CONFIG_TRACING
 	/* state flags for use by tracers */
 	unsigned long trace;
-	/* bitmask of trace recursion */
+	/* bitmask and counter of trace recursion */
 	unsigned long trace_recursion;
 #endif /* CONFIG_TRACING */
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 25949b3..1ee417f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -109,12 +109,18 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
 static void ftrace_global_list_func(unsigned long ip,
 				    unsigned long parent_ip)
 {
-	struct ftrace_ops *op = rcu_dereference_raw(ftrace_global_list); /*see above*/
+	struct ftrace_ops *op;
+
+	if (unlikely(trace_recursion_test(TRACE_GLOBAL_BIT)))
+		return;
 
+	trace_recursion_set(TRACE_GLOBAL_BIT);
+	op = rcu_dereference_raw(ftrace_global_list); /*see above*/
 	while (op != &ftrace_list_end) {
 		op->func(ip, parent_ip);
 		op = rcu_dereference_raw(op->next); /*see above*/
 	};
+	trace_recursion_clear(TRACE_GLOBAL_BIT);
 }
 
 static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
@@ -3490,6 +3496,10 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
 {
 	struct ftrace_ops *op;
 
+	if (unlikely(trace_recursion_test(TRACE_INTERNAL_BIT)))
+		return;
+
+	trace_recursion_set(TRACE_INTERNAL_BIT);
 	/*
 	 * Some of the ops may be dynamically allocated,
 	 * they must be freed after a synchronize_sched().
@@ -3502,6 +3512,7 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
 		op = rcu_dereference_raw(op->next);
 	};
 	preempt_enable_notrace();
+	trace_recursion_clear(TRACE_INTERNAL_BIT);
 }
 
 static void clear_ftrace_swapper(void)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 0ef7b4b..b0c7aa4 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2216,7 +2216,7 @@ static noinline void trace_recursive_fail(void)
 
 	printk_once(KERN_WARNING "Tracing recursion: depth[%ld]:"
 		    "HC[%lu]:SC[%lu]:NMI[%lu]\n",
-		    current->trace_recursion,
+		    trace_recursion_buffer(),
 		    hardirq_count() >> HARDIRQ_SHIFT,
 		    softirq_count() >> SOFTIRQ_SHIFT,
 		    in_nmi());
@@ -2226,9 +2226,9 @@ static noinline void trace_recursive_fail(void)
 
 static inline int trace_recursive_lock(void)
 {
-	current->trace_recursion++;
+	trace_recursion_inc();
 
-	if (likely(current->trace_recursion < TRACE_RECURSIVE_DEPTH))
+	if (likely(trace_recursion_buffer() < TRACE_RECURSIVE_DEPTH))
 		return 0;
 
 	trace_recursive_fail();
@@ -2238,9 +2238,9 @@ static inline int trace_recursive_lock(void)
 
 static inline void trace_recursive_unlock(void)
 {
-	WARN_ON_ONCE(!current->trace_recursion);
+	WARN_ON_ONCE(!trace_recursion_buffer());
 
-	current->trace_recursion--;
+	trace_recursion_dec();
 }
 
 #else
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6b69c4b..229f859 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -784,4 +784,19 @@ extern const char *__stop___trace_bprintk_fmt[];
 	FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))
 #include "trace_entries.h"
 
+/* Only current can touch trace_recursion */
+#define trace_recursion_inc() do { (current)->trace_recursion++; } while (0)
+#define trace_recursion_dec() do { (current)->trace_recursion--; } while (0)
+
+/* Ring buffer has the 10 LSB bits to count */
+#define trace_recursion_buffer() ((current)->trace_recursion & 0x3ff)
+
+/* for function tracing recursion */
+#define TRACE_INTERNAL_BIT		(1<<11)
+#define TRACE_GLOBAL_BIT		(1<<12)
+
+#define trace_recursion_set(bit)	do { (current)->trace_recursion |= (bit); } while (0)
+#define trace_recursion_clear(bit)	do { (current)->trace_recursion &= ~(bit); } while (0)
+#define trace_recursion_test(bit)	((current)->trace_recursion & (bit))
+
 #endif /* _LINUX_KERNEL_TRACE_H */
-- 
1.7.4.4

Re: [PATCH 12/12] ftrace: Add internal recursive checks

[Witold Baryluk]

[-- Attachment #1: Type: text/plain, Size: 1926 bytes --]

On 05-26 11:25, Steven Rostedt wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
> 
> Witold reported a reboot caused by the selftests of the dynamic function
> tracer. He sent me a config and I used ktest to do a config_bisect on it
> (as my config did not cause the crash). It pointed out that the problem
> config was CONFIG_PROVE_RCU.

Just disabling PROVE_RCU in my config
make crash disapear, so it is good diagnosis. Good work.

> 
> What happened was that if multiple callbacks are attached to the
> function tracer, we iterate a list of callbacks. Because the list is
> managed by synchronize_sched() and preempt_disable, the access to the
> pointers uses rcu_dereference_raw().
> 
> When PROVE_RCU is enabled, the rcu_dereference_raw() calls some
> debugging functions, which happen to be traced. The tracing of the debug
> function would then call rcu_dereference_raw() which would then call the
> debug function and then... well you get the idea.
> 
> I first wrote two different patches to solve this bug.
> 
> 1) add a __rcu_dereference_raw() that would not do any checks.
> 2) add notrace to the offending debug functions.
> 
> Both of these patches worked.
> 
> Talking with Paul McKenney on IRC, he suggested to add recursion
> detection instead. This seemed to be a better solution, so I decided to
> implement it. As the task_struct already has a trace_recursion to detect
> recursion in the ring buffer, and that has a very small number it
> allows, I decided to use that same variable to add flags that can detect
> the recursion inside the infrastructure of the function tracer.
> 
> I plan to change it so that the task struct bit can be checked in
> mcount, but as that requires changes to all archs, I will hold that off
> to the next merge window.

I'm testing this patch now, and do not see any problem right now.

Regards,
Witek

-- 
Witold Baryluk

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 198 bytes --]

Re: [PATCH 12/12] ftrace: Add internal recursive checks

[Paul E. McKenney]

On Thu, May 26, 2011 at 11:25:54AM -0400, Steven Rostedt wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
> 
> Witold reported a reboot caused by the selftests of the dynamic function
> tracer. He sent me a config and I used ktest to do a config_bisect on it
> (as my config did not cause the crash). It pointed out that the problem
> config was CONFIG_PROVE_RCU.
> 
> What happened was that if multiple callbacks are attached to the
> function tracer, we iterate a list of callbacks. Because the list is
> managed by synchronize_sched() and preempt_disable, the access to the
> pointers uses rcu_dereference_raw().
> 
> When PROVE_RCU is enabled, the rcu_dereference_raw() calls some
> debugging functions, which happen to be traced. The tracing of the debug
> function would then call rcu_dereference_raw() which would then call the
> debug function and then... well you get the idea.
> 
> I first wrote two different patches to solve this bug.
> 
> 1) add a __rcu_dereference_raw() that would not do any checks.
> 2) add notrace to the offending debug functions.
> 
> Both of these patches worked.
> 
> Talking with Paul McKenney on IRC, he suggested to add recursion
> detection instead. This seemed to be a better solution, so I decided to
> implement it. As the task_struct already has a trace_recursion to detect
> recursion in the ring buffer, and that has a very small number it
> allows, I decided to use that same variable to add flags that can detect
> the recursion inside the infrastructure of the function tracer.
> 
> I plan to change it so that the task struct bit can be checked in
> mcount, but as that requires changes to all archs, I will hold that off
> to the next merge window.

Looks good to me.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Link: http://lkml.kernel.org/r/1306348063.1465.116.camel@gandalf.stny.rr.com
> Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  include/linux/sched.h      |    2 +-
>  kernel/trace/ftrace.c      |   13 ++++++++++++-
>  kernel/trace/ring_buffer.c |   10 +++++-----
>  kernel/trace/trace.h       |   15 +++++++++++++++
>  4 files changed, 33 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index d8b2d0b..7b78d9c 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1513,7 +1513,7 @@ struct task_struct {
>  #ifdef CONFIG_TRACING
>  	/* state flags for use by tracers */
>  	unsigned long trace;
> -	/* bitmask of trace recursion */
> +	/* bitmask and counter of trace recursion */
>  	unsigned long trace_recursion;
>  #endif /* CONFIG_TRACING */
>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 25949b3..1ee417f 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -109,12 +109,18 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
>  static void ftrace_global_list_func(unsigned long ip,
>  				    unsigned long parent_ip)
>  {
> -	struct ftrace_ops *op = rcu_dereference_raw(ftrace_global_list); /*see above*/
> +	struct ftrace_ops *op;
> +
> +	if (unlikely(trace_recursion_test(TRACE_GLOBAL_BIT)))
> +		return;
> 
> +	trace_recursion_set(TRACE_GLOBAL_BIT);
> +	op = rcu_dereference_raw(ftrace_global_list); /*see above*/
>  	while (op != &ftrace_list_end) {
>  		op->func(ip, parent_ip);
>  		op = rcu_dereference_raw(op->next); /*see above*/
>  	};
> +	trace_recursion_clear(TRACE_GLOBAL_BIT);
>  }
> 
>  static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
> @@ -3490,6 +3496,10 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
>  {
>  	struct ftrace_ops *op;
> 
> +	if (unlikely(trace_recursion_test(TRACE_INTERNAL_BIT)))
> +		return;
> +
> +	trace_recursion_set(TRACE_INTERNAL_BIT);
>  	/*
>  	 * Some of the ops may be dynamically allocated,
>  	 * they must be freed after a synchronize_sched().
> @@ -3502,6 +3512,7 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
>  		op = rcu_dereference_raw(op->next);
>  	};
>  	preempt_enable_notrace();
> +	trace_recursion_clear(TRACE_INTERNAL_BIT);
>  }
> 
>  static void clear_ftrace_swapper(void)
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index 0ef7b4b..b0c7aa4 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -2216,7 +2216,7 @@ static noinline void trace_recursive_fail(void)
> 
>  	printk_once(KERN_WARNING "Tracing recursion: depth[%ld]:"
>  		    "HC[%lu]:SC[%lu]:NMI[%lu]\n",
> -		    current->trace_recursion,
> +		    trace_recursion_buffer(),
>  		    hardirq_count() >> HARDIRQ_SHIFT,
>  		    softirq_count() >> SOFTIRQ_SHIFT,
>  		    in_nmi());
> @@ -2226,9 +2226,9 @@ static noinline void trace_recursive_fail(void)
> 
>  static inline int trace_recursive_lock(void)
>  {
> -	current->trace_recursion++;
> +	trace_recursion_inc();
> 
> -	if (likely(current->trace_recursion < TRACE_RECURSIVE_DEPTH))
> +	if (likely(trace_recursion_buffer() < TRACE_RECURSIVE_DEPTH))
>  		return 0;
> 
>  	trace_recursive_fail();
> @@ -2238,9 +2238,9 @@ static inline int trace_recursive_lock(void)
> 
>  static inline void trace_recursive_unlock(void)
>  {
> -	WARN_ON_ONCE(!current->trace_recursion);
> +	WARN_ON_ONCE(!trace_recursion_buffer());
> 
> -	current->trace_recursion--;
> +	trace_recursion_dec();
>  }
> 
>  #else
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 6b69c4b..229f859 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -784,4 +784,19 @@ extern const char *__stop___trace_bprintk_fmt[];
>  	FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))
>  #include "trace_entries.h"
> 
> +/* Only current can touch trace_recursion */
> +#define trace_recursion_inc() do { (current)->trace_recursion++; } while (0)
> +#define trace_recursion_dec() do { (current)->trace_recursion--; } while (0)
> +
> +/* Ring buffer has the 10 LSB bits to count */
> +#define trace_recursion_buffer() ((current)->trace_recursion & 0x3ff)
> +
> +/* for function tracing recursion */
> +#define TRACE_INTERNAL_BIT		(1<<11)
> +#define TRACE_GLOBAL_BIT		(1<<12)
> +
> +#define trace_recursion_set(bit)	do { (current)->trace_recursion |= (bit); } while (0)
> +#define trace_recursion_clear(bit)	do { (current)->trace_recursion &= ~(bit); } while (0)
> +#define trace_recursion_test(bit)	((current)->trace_recursion & (bit))
> +
>  #endif /* _LINUX_KERNEL_TRACE_H */
> -- 
> 1.7.4.4
> 
> 

Re: [PATCH 00/12] [GIT PULL] tracing: fixes

[Ingo Molnar]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> 
> Ingo,
> 
> This patch set contains all fixes. Some of the fixes are to get
> rid of warnings, but I think getting rid of warnings is a good thing
> during a merge window.
> 
> What's different about this and my last pull request:
> 
> 1) I removed the two patches that were not bug fixes and put them
>    in my queue for 2.6.41/3.1/2.8.1
> 
> 2) I added two patches, one that was a bug fix that caused a
>    triple fault when PROVE_RCU was set, and the other that caused
>    problems with truncating 64bit words in the trace events.
> 
> 3) I pulled out Masami's kprobe stack trace fix because it failed
>    on other archs. My last push request, I did compile test other
>    archs, but I only used the default config. This time, I enabled
>    tracing as well (doing it both with and without tracing enabled)
>    and when tracing was enabled, I detected the problem with the lack
>    of save_stack_trace_regs() in other archs.
> 
> I tested this on x86_64 and x86_32 as well as compiled tested for
> the following archs, with and without tracing enabled:
> 
>  alpha, arm, blackfin, ia64, parsic, ppc, ppc64, sparc
> 
> The following had failures for other reason (failed without this
> patch set):
> 
>   cris, cris32, m68k, mips64, mips32, parsic64, sh, xtensa, uml.
> 
> 
> Please pull the latest tip/perf/urgent tree, which can be found at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
> tip/perf/urgent
> 
> 
> Jiri Olsa (1):
>       jump_label: Check entries limit in __jump_label_update
> 
> Rabin Vincent (1):
>       ftrace/recordmcount: Avoid STT_FUNC symbols as base on ARM
> 
> Rakib Mullick (1):
>       x86/ftrace: Fix compiler warning in ftrace.c
> 
> Steven Rostedt (7):
>       maccess,probe_kernel: Make write/read src const void *
>       scripts/tags.sh: Fix ctags for DEFINE_EVENT()
>       scripts/tags.sh: Add magic for trace-events for etags too
>       ftrace: Have ftrace_startup() return failure code
>       tracing: Have event with function tracer check error return
>       ftrace: Set ops->flag to enabled even on static function tracing
>       ftrace: Add internal recursive checks
> 
> liubo (2):
>       tracing: Add __print_symbolic_u64 to avoid warnings on 32bit machine
>       tracing: Update btrfs's tracepoints to use u64 interface
> 
> ----
>  arch/blackfin/mm/maccess.c   |    4 ++--
>  arch/s390/mm/maccess.c       |    4 ++--
>  arch/x86/kernel/ftrace.c     |   12 ++++++------
>  include/linux/ftrace_event.h |   12 ++++++++++++
>  include/linux/sched.h        |    2 +-
>  include/linux/uaccess.h      |    8 ++++----
>  include/trace/events/btrfs.h |    4 ++--
>  include/trace/ftrace.h       |   13 +++++++++++++
>  kernel/jump_label.c          |   18 +++++++++++++-----
>  kernel/trace/ftrace.c        |   31 ++++++++++++++++++++++++-------
>  kernel/trace/ring_buffer.c   |   10 +++++-----
>  kernel/trace/trace.h         |   15 +++++++++++++++
>  kernel/trace/trace_events.c  |    7 ++++++-
>  kernel/trace/trace_output.c  |   27 +++++++++++++++++++++++++++
>  mm/maccess.c                 |    8 ++++----
>  scripts/recordmcount.h       |    8 ++++++++
>  scripts/tags.sh              |    6 ++++--
>  17 files changed, 148 insertions(+), 41 deletions(-)

Pulled, thanks a lot Steve!

	Ingo