* [PATCH 0/1] Put seq_buf on a diet
@ 2023-10-19 19:45 Matthew Wilcox (Oracle)
2023-10-19 19:45 ` [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq Matthew Wilcox (Oracle)
2023-10-19 21:14 ` [PATCH 0/1] Put seq_buf on a diet Steven Rostedt
0 siblings, 2 replies; 7+ messages in thread
From: Matthew Wilcox (Oracle) @ 2023-10-19 19:45 UTC (permalink / raw)
To: Steven Rostedt
Cc: Matthew Wilcox (Oracle),
Kees Cook, Christoph Hellwig, Justin Stitt, linux-hardening,
linux-kernel, Kent Overstreet, Petr Mladek, Andy Shevchenko,
Rasmus Villemoes, Sergey Senozhatsky
Prompted by the recent mails on ksummit, let's actually try to make this
work this time. We need a container for manipulating strings easily,
and seq_buf is the closest thing we have to it. The only problem I have
with it is the readpos that is only useful for the tracing code today.
So move it from the seq_buf to the tracing code.
We should go further with this patch series, including using seq_buf
within vsprintf, but if we can't get over this hurdle first, I'm not
going to waste my time on this again.
Matthew Wilcox (Oracle) (1):
trace: Move readpos from seq_buf to trace_seq
include/linux/seq_buf.h | 5 +----
include/linux/trace_seq.h | 2 ++
kernel/trace/trace.c | 10 +++++-----
kernel/trace/trace_seq.c | 6 +++++-
lib/seq_buf.c | 13 +++++--------
5 files changed, 18 insertions(+), 18 deletions(-)
--
2.40.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq
2023-10-19 19:45 [PATCH 0/1] Put seq_buf on a diet Matthew Wilcox (Oracle)
@ 2023-10-19 19:45 ` Matthew Wilcox (Oracle)
2023-10-19 21:59 ` kernel test robot
2023-10-19 21:14 ` [PATCH 0/1] Put seq_buf on a diet Steven Rostedt
1 sibling, 1 reply; 7+ messages in thread
From: Matthew Wilcox (Oracle) @ 2023-10-19 19:45 UTC (permalink / raw)
To: Steven Rostedt
Cc: Matthew Wilcox (Oracle),
Kees Cook, Christoph Hellwig, Justin Stitt, linux-hardening,
linux-kernel, Kent Overstreet, Petr Mladek, Andy Shevchenko,
Rasmus Villemoes, Sergey Senozhatsky
To make seq_buf more lightweight as a string buf, move the readpos member
from seq_buf to its container, trace_seq. That puts the responsibility
of maintaining the readpos entirely in the tracing code. If some future
users want to package up the readpos with a seq_buf, we can define a
new struct then.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/seq_buf.h | 5 +----
include/linux/trace_seq.h | 2 ++
kernel/trace/trace.c | 10 +++++-----
kernel/trace/trace_seq.c | 6 +++++-
lib/seq_buf.c | 13 +++++--------
5 files changed, 18 insertions(+), 18 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 515d7fcb9634..a0fb013cebdf 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -14,19 +14,16 @@
* @buffer: pointer to the buffer
* @size: size of the buffer
* @len: the amount of data inside the buffer
- * @readpos: The next position to read in the buffer.
*/
struct seq_buf {
char *buffer;
size_t size;
size_t len;
- loff_t readpos;
};
static inline void seq_buf_clear(struct seq_buf *s)
{
s->len = 0;
- s->readpos = 0;
}
static inline void
@@ -143,7 +140,7 @@ extern __printf(2, 0)
int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
- int cnt);
+ size_t start, int cnt);
extern int seq_buf_puts(struct seq_buf *s, const char *str);
extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 6be92bf559fe..3691e0e76a1a 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -14,6 +14,7 @@
struct trace_seq {
char buffer[PAGE_SIZE];
struct seq_buf seq;
+ size_t readpos;
int full;
};
@@ -22,6 +23,7 @@ trace_seq_init(struct trace_seq *s)
{
seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
s->full = 0;
+ s->readpos = 0;
}
/**
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index abaaf516fcae..217cabd09c3e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1730,15 +1730,15 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
int len;
- if (trace_seq_used(s) <= s->seq.readpos)
+ if (trace_seq_used(s) <= s->readpos)
return -EBUSY;
- len = trace_seq_used(s) - s->seq.readpos;
+ len = trace_seq_used(s) - s->readpos;
if (cnt > len)
cnt = len;
- memcpy(buf, s->buffer + s->seq.readpos, cnt);
+ memcpy(buf, s->buffer + s->readpos, cnt);
- s->seq.readpos += cnt;
+ s->readpos += cnt;
return cnt;
}
@@ -7006,7 +7006,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
/* Now copy what we have to the user */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
- if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
+ if (iter->seq.readpos >= trace_seq_used(&iter->seq))
trace_seq_init(&iter->seq);
/*
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index bac06ee3b98b..7be97229ddf8 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -370,8 +370,12 @@ EXPORT_SYMBOL_GPL(trace_seq_path);
*/
int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
{
+ int ret;
__trace_seq_init(s);
- return seq_buf_to_user(&s->seq, ubuf, cnt);
+ ret = seq_buf_to_user(&s->seq, ubuf, s->readpos, cnt);
+ if (ret > 0)
+ s->readpos += ret;
+ return ret;
}
EXPORT_SYMBOL_GPL(trace_seq_to_user);
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index 45c450f423fa..0d218f3835ae 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -340,7 +340,7 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
*
* Returns -EFAULT if the copy to userspace fails.
*/
-int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt)
{
int len;
int ret;
@@ -350,20 +350,17 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
len = seq_buf_used(s);
- if (len <= s->readpos)
+ if (len <= start)
return -EBUSY;
- len -= s->readpos;
+ len -= start;
if (cnt > len)
cnt = len;
- ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+ ret = copy_to_user(ubuf, s->buffer + start, cnt);
if (ret == cnt)
return -EFAULT;
- cnt -= ret;
-
- s->readpos += cnt;
- return cnt;
+ return cnt - ret;
}
/**
--
2.40.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 0/1] Put seq_buf on a diet
2023-10-19 19:45 [PATCH 0/1] Put seq_buf on a diet Matthew Wilcox (Oracle)
2023-10-19 19:45 ` [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq Matthew Wilcox (Oracle)
@ 2023-10-19 21:14 ` Steven Rostedt
2023-10-19 21:18 ` Steven Rostedt
1 sibling, 1 reply; 7+ messages in thread
From: Steven Rostedt @ 2023-10-19 21:14 UTC (permalink / raw)
To: Matthew Wilcox (Oracle)
Cc: Kees Cook, Christoph Hellwig, Justin Stitt, linux-hardening,
linux-kernel, Kent Overstreet, Petr Mladek, Andy Shevchenko,
Rasmus Villemoes, Sergey Senozhatsky
On Thu, 19 Oct 2023 20:45:13 +0100
"Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:
> Prompted by the recent mails on ksummit, let's actually try to make this
> work this time. We need a container for manipulating strings easily,
> and seq_buf is the closest thing we have to it. The only problem I have
> with it is the readpos that is only useful for the tracing code today.
> So move it from the seq_buf to the tracing code.
>
> We should go further with this patch series, including using seq_buf
> within vsprintf, but if we can't get over this hurdle first, I'm not
> going to waste my time on this again.
>
> Matthew Wilcox (Oracle) (1):
> trace: Move readpos from seq_buf to trace_seq
>
> include/linux/seq_buf.h | 5 +----
> include/linux/trace_seq.h | 2 ++
> kernel/trace/trace.c | 10 +++++-----
> kernel/trace/trace_seq.c | 6 +++++-
> lib/seq_buf.c | 13 +++++--------
> 5 files changed, 18 insertions(+), 18 deletions(-)
>
Thanks Matthew, I'll pull this in and add it to my for-next queue (after
testing)
-- Steve
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 0/1] Put seq_buf on a diet
2023-10-19 21:14 ` [PATCH 0/1] Put seq_buf on a diet Steven Rostedt
@ 2023-10-19 21:18 ` Steven Rostedt
0 siblings, 0 replies; 7+ messages in thread
From: Steven Rostedt @ 2023-10-19 21:18 UTC (permalink / raw)
To: Matthew Wilcox (Oracle)
Cc: Kees Cook, Christoph Hellwig, Justin Stitt, linux-hardening,
linux-kernel, Kent Overstreet, Petr Mladek, Andy Shevchenko,
Rasmus Villemoes, Sergey Senozhatsky
On Thu, 19 Oct 2023 17:14:39 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 19 Oct 2023 20:45:13 +0100
> "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:
>
> > Prompted by the recent mails on ksummit, let's actually try to make this
> > work this time. We need a container for manipulating strings easily,
> > and seq_buf is the closest thing we have to it. The only problem I have
> > with it is the readpos that is only useful for the tracing code today.
> > So move it from the seq_buf to the tracing code.
> >
> > We should go further with this patch series, including using seq_buf
> > within vsprintf, but if we can't get over this hurdle first, I'm not
> > going to waste my time on this again.
> >
> > Matthew Wilcox (Oracle) (1):
> > trace: Move readpos from seq_buf to trace_seq
> >
> > include/linux/seq_buf.h | 5 +----
> > include/linux/trace_seq.h | 2 ++
> > kernel/trace/trace.c | 10 +++++-----
> > kernel/trace/trace_seq.c | 6 +++++-
> > lib/seq_buf.c | 13 +++++--------
> > 5 files changed, 18 insertions(+), 18 deletions(-)
> >
>
> Thanks Matthew, I'll pull this in and add it to my for-next queue (after
> testing)
Actually,
Can you resend it, and Cc: linux-trace-kernel@vger.kernel.org so that it
goes into patchwork.
Thanks!
-- Steve
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq
2023-10-19 19:45 ` [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq Matthew Wilcox (Oracle)
@ 2023-10-19 21:59 ` kernel test robot
2023-10-19 22:09 ` Steven Rostedt
0 siblings, 1 reply; 7+ messages in thread
From: kernel test robot @ 2023-10-19 21:59 UTC (permalink / raw)
To: Matthew Wilcox (Oracle), Steven Rostedt
Cc: oe-kbuild-all, Matthew Wilcox (Oracle),
Kees Cook, Christoph Hellwig, Justin Stitt, linux-hardening,
linux-kernel, Kent Overstreet, Petr Mladek, Andy Shevchenko,
Rasmus Villemoes, Sergey Senozhatsky
Hi Matthew,
kernel test robot noticed the following build warnings:
[auto build test WARNING on kees/for-next/pstore]
[also build test WARNING on kees/for-next/kspp linus/master v6.6-rc6 next-20231019]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/trace-Move-readpos-from-seq_buf-to-trace_seq/20231020-034718
base: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/pstore
patch link: https://lore.kernel.org/r/20231019194514.2115506-2-willy%40infradead.org
patch subject: [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20231020/202310200523.ggyHvT6w-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231020/202310200523.ggyHvT6w-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310200523.ggyHvT6w-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> lib/seq_buf.c:344: warning: Function parameter or member 'start' not described in 'seq_buf_to_user'
vim +344 lib/seq_buf.c
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 322)
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 323) /**
9dbbc3b9d09d6d lib/seq_buf.c Zhen Lei 2021-07-07 324 * seq_buf_to_user - copy the sequence buffer to user space
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 325) * @s: seq_buf descriptor
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 326) * @ubuf: The userspace memory location to copy to
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 327) * @cnt: The amount to copy
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 328) *
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 329) * Copies the sequence buffer into the userspace memory pointed to
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 330) * by @ubuf. It starts from the last read position (@s->readpos)
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 331) * and writes up to @cnt characters or till it reaches the end of
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 332) * the content in the buffer (@s->len), which ever comes first.
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 333) *
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 334) * On success, it returns a positive number of the number of bytes
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 335) * it copied.
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 336) *
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 337) * On failure it returns -EBUSY if all of the content in the
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 338) * sequence has been already read, which includes nothing in the
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 339) * sequence (@s->len == @s->readpos).
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 340) *
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 341) * Returns -EFAULT if the copy to userspace fails.
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 342) */
9377093a882be0 lib/seq_buf.c Matthew Wilcox (Oracle 2023-10-19 343) int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt)
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 @344) {
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 345) int len;
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 346) int ret;
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 347)
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 348) if (!cnt)
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 349) return 0;
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 350)
ff078d8fc64472 lib/seq_buf.c Jerry Snitselaar 2015-11-16 351 len = seq_buf_used(s);
ff078d8fc64472 lib/seq_buf.c Jerry Snitselaar 2015-11-16 352
9377093a882be0 lib/seq_buf.c Matthew Wilcox (Oracle 2023-10-19 353) if (len <= start)
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 354) return -EBUSY;
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 355)
9377093a882be0 lib/seq_buf.c Matthew Wilcox (Oracle 2023-10-19 356) len -= start;
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 357) if (cnt > len)
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 358) cnt = len;
9377093a882be0 lib/seq_buf.c Matthew Wilcox (Oracle 2023-10-19 359) ret = copy_to_user(ubuf, s->buffer + start, cnt);
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 360) if (ret == cnt)
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 361) return -EFAULT;
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 362)
9377093a882be0 lib/seq_buf.c Matthew Wilcox (Oracle 2023-10-19 363) return cnt - ret;
3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 364) }
353cade3149c27 lib/seq_buf.c Piotr Maziarz 2019-11-07 365
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq
2023-10-19 21:59 ` kernel test robot
@ 2023-10-19 22:09 ` Steven Rostedt
0 siblings, 0 replies; 7+ messages in thread
From: Steven Rostedt @ 2023-10-19 22:09 UTC (permalink / raw)
To: kernel test robot
Cc: Matthew Wilcox (Oracle),
oe-kbuild-all, Kees Cook, Christoph Hellwig, Justin Stitt,
linux-hardening, linux-kernel, Kent Overstreet, Petr Mladek,
Andy Shevchenko, Rasmus Villemoes, Sergey Senozhatsky
On Fri, 20 Oct 2023 05:59:36 +0800
kernel test robot <lkp@intel.com> wrote:
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 323) /**
> 9dbbc3b9d09d6d lib/seq_buf.c Zhen Lei 2021-07-07 324 * seq_buf_to_user - copy the sequence buffer to user space
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 325) * @s: seq_buf descriptor
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 326) * @ubuf: The userspace memory location to copy to
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 327) * @cnt: The amount to copy
When you resend, I guess you should add the @start as well.
-- Steve
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 328) *
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 329) * Copies the sequence buffer into the userspace memory pointed to
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 330) * by @ubuf. It starts from the last read position (@s->readpos)
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 331) * and writes up to @cnt characters or till it reaches the end of
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 332) * the content in the buffer (@s->len), which ever comes first.
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 333) *
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 334) * On success, it returns a positive number of the number of bytes
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 335) * it copied.
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 336) *
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 337) * On failure it returns -EBUSY if all of the content in the
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 338) * sequence has been already read, which includes nothing in the
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 339) * sequence (@s->len == @s->readpos).
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 340) *
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 341) * Returns -EFAULT if the copy to userspace fails.
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 342) */
> 9377093a882be0 lib/seq_buf.c Matthew Wilcox (Oracle 2023-10-19 343) int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt)
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 @344) {
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 345) int len;
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 346) int ret;
> 3a161d99c43ce7 kernel/trace/seq_buf.c Steven Rostedt (Red Hat 2014-06-25 347)
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq
@ 2023-10-19 21:40 Matthew Wilcox (Oracle)
0 siblings, 0 replies; 7+ messages in thread
From: Matthew Wilcox (Oracle) @ 2023-10-19 21:40 UTC (permalink / raw)
To: Steven Rostedt
Cc: Matthew Wilcox (Oracle),
Kees Cook, Christoph Hellwig, Justin Stitt, linux-hardening,
linux-kernel, linux-trace-kernel, Kent Overstreet, Petr Mladek,
Andy Shevchenko, Rasmus Villemoes, Sergey Senozhatsky
To make seq_buf more lightweight as a string buf, move the readpos member
from seq_buf to its container, trace_seq. That puts the responsibility
of maintaining the readpos entirely in the tracing code. If some future
users want to package up the readpos with a seq_buf, we can define a
new struct then.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/seq_buf.h | 5 +----
include/linux/trace_seq.h | 2 ++
kernel/trace/trace.c | 10 +++++-----
kernel/trace/trace_seq.c | 6 +++++-
lib/seq_buf.c | 13 +++++--------
5 files changed, 18 insertions(+), 18 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 515d7fcb9634..a0fb013cebdf 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -14,19 +14,16 @@
* @buffer: pointer to the buffer
* @size: size of the buffer
* @len: the amount of data inside the buffer
- * @readpos: The next position to read in the buffer.
*/
struct seq_buf {
char *buffer;
size_t size;
size_t len;
- loff_t readpos;
};
static inline void seq_buf_clear(struct seq_buf *s)
{
s->len = 0;
- s->readpos = 0;
}
static inline void
@@ -143,7 +140,7 @@ extern __printf(2, 0)
int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
- int cnt);
+ size_t start, int cnt);
extern int seq_buf_puts(struct seq_buf *s, const char *str);
extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 6be92bf559fe..3691e0e76a1a 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -14,6 +14,7 @@
struct trace_seq {
char buffer[PAGE_SIZE];
struct seq_buf seq;
+ size_t readpos;
int full;
};
@@ -22,6 +23,7 @@ trace_seq_init(struct trace_seq *s)
{
seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
s->full = 0;
+ s->readpos = 0;
}
/**
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index abaaf516fcae..217cabd09c3e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1730,15 +1730,15 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
int len;
- if (trace_seq_used(s) <= s->seq.readpos)
+ if (trace_seq_used(s) <= s->readpos)
return -EBUSY;
- len = trace_seq_used(s) - s->seq.readpos;
+ len = trace_seq_used(s) - s->readpos;
if (cnt > len)
cnt = len;
- memcpy(buf, s->buffer + s->seq.readpos, cnt);
+ memcpy(buf, s->buffer + s->readpos, cnt);
- s->seq.readpos += cnt;
+ s->readpos += cnt;
return cnt;
}
@@ -7006,7 +7006,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
/* Now copy what we have to the user */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
- if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
+ if (iter->seq.readpos >= trace_seq_used(&iter->seq))
trace_seq_init(&iter->seq);
/*
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index bac06ee3b98b..7be97229ddf8 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -370,8 +370,12 @@ EXPORT_SYMBOL_GPL(trace_seq_path);
*/
int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
{
+ int ret;
__trace_seq_init(s);
- return seq_buf_to_user(&s->seq, ubuf, cnt);
+ ret = seq_buf_to_user(&s->seq, ubuf, s->readpos, cnt);
+ if (ret > 0)
+ s->readpos += ret;
+ return ret;
}
EXPORT_SYMBOL_GPL(trace_seq_to_user);
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index 45c450f423fa..0d218f3835ae 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -340,7 +340,7 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
*
* Returns -EFAULT if the copy to userspace fails.
*/
-int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt)
{
int len;
int ret;
@@ -350,20 +350,17 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
len = seq_buf_used(s);
- if (len <= s->readpos)
+ if (len <= start)
return -EBUSY;
- len -= s->readpos;
+ len -= start;
if (cnt > len)
cnt = len;
- ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+ ret = copy_to_user(ubuf, s->buffer + start, cnt);
if (ret == cnt)
return -EFAULT;
- cnt -= ret;
-
- s->readpos += cnt;
- return cnt;
+ return cnt - ret;
}
/**
--
2.40.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2023-10-19 22:09 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-10-19 19:45 [PATCH 0/1] Put seq_buf on a diet Matthew Wilcox (Oracle)
2023-10-19 19:45 ` [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq Matthew Wilcox (Oracle)
2023-10-19 21:59 ` kernel test robot
2023-10-19 22:09 ` Steven Rostedt
2023-10-19 21:14 ` [PATCH 0/1] Put seq_buf on a diet Steven Rostedt
2023-10-19 21:18 ` Steven Rostedt
2023-10-19 21:40 [PATCH 1/1] trace: Move readpos from seq_buf to trace_seq Matthew Wilcox (Oracle)
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