6.6-stable review patch. If anyone has any objections, please let me know.
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From: Matthew Wilcox (Oracle) willy@infradead.org
[ Upstream commit d0ed46b60396cfa7e0056f55e1ce0b43c7db57b6 ]
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.
Link: https://lore.kernel.org/linux-trace-kernel/20231020033545.2587554-2-willy@in...
Cc: Kees Cook keescook@chromium.org Cc: Justin Stitt justinstitt@google.com Cc: Kent Overstreet kent.overstreet@linux.dev Cc: Petr Mladek pmladek@suse.com Cc: Andy Shevchenko andriy.shevchenko@linux.intel.com Cc: Rasmus Villemoes linux@rasmusvillemoes.dk Cc: Sergey Senozhatsky senozhatsky@chromium.org Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Reviewed-by: Christoph Hellwig hch@lst.de Acked-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Stable-dep-of: afd2627f727b ("tracing: Check "%s" dereference via the field and not the TP_printk format") Signed-off-by: Sasha Levin sashal@kernel.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 | 22 ++++++++++------------ 5 files changed, 23 insertions(+), 22 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 220903117c51..83f6ef4d7419 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1731,15 +1731,15 @@ 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; }
@@ -7011,7 +7011,7 @@ 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..b7477aefff53 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -324,23 +324,24 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc) * seq_buf_to_user - copy the sequence buffer to user space * @s: seq_buf descriptor * @ubuf: The userspace memory location to copy to + * @start: The first byte in the buffer to copy * @cnt: The amount to copy * * Copies the sequence buffer into the userspace memory pointed to - * by @ubuf. It starts from the last read position (@s->readpos) - * and writes up to @cnt characters or till it reaches the end of - * the content in the buffer (@s->len), which ever comes first. + * by @ubuf. It starts from @start and writes up to @cnt characters + * or until it reaches the end of the content in the buffer (@s->len), + * whichever comes first. * * On success, it returns a positive number of the number of bytes * it copied. * * On failure it returns -EBUSY if all of the content in the * sequence has been already read, which includes nothing in the - * sequence (@s->len == @s->readpos). + * sequence (@s->len == @start). * * 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 +351,17 @@ 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; }
/**