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SubjectRe: [PATCH 10/26] dynamic_debug: enlarge command/query write buffer
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On Wed, 2011-09-21 at 15:54 -0600, jim.cromie@gmail.com wrote:
> From: Jim Cromie <jim.cromie@gmail.com>
>
> Current write buffer is 256 bytes, on stack. Allocate it off heap,
> and enlarge it to 4096 bytes, big enough for ~100 queries (at 40 bytes
> each), and error out if not. This should be enough for most uses, and
> others can be split into 2 writes.
>
> This makes it play nicely with:
> $> cat debug-queries-file > /dbg/dynamic_debug/control
[]
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
[]
> @@ -590,24 +590,32 @@ __setup("ddebug_query=", ddebug_setup_query);
> * File_ops->write method for <debugfs>/dynamic_debug/conrol. Gathers the
> * command text from userspace, parses and executes it.
> */
> +#define USER_BUF_PAGE 4095

Why not just read into a fifo and parse
it until empty?

> static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
> size_t len, loff_t *offp)
> {
> - char tmpbuf[256];
> + char *tmpbuf;
> int ret;
>
> if (len == 0)
> return 0;
> - /* we don't check *offp -- multiple writes() are allowed */
> - if (len > sizeof(tmpbuf)-1)
> + if (len > USER_BUF_PAGE - 1) {
> + pr_warn("expected <%d bytes into control \n", USER_BUF_PAGE);
> return -E2BIG;
> - if (copy_from_user(tmpbuf, ubuf, len))
> + }

kfifo_from_user?




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