Messages in this thread Patch in this message | | | From | jim.cromie@gmail ... | Subject | [PATCH 14/25] dynamic_debug: enlarge command/query write buffer | Date | Mon, 12 Dec 2011 16:12:40 -0700 |
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From: Jim Cromie <jim.cromie@gmail.com>
Current query write buffer is 256 bytes, on stack. In comparison, the ddebug_query boot-arg is 1024. Allocate the buffer off heap, and enlarge it to 4096 bytes, big enough for ~100 queries (at 40 bytes each), and error out if not. This makes it play nicely with large query sets (to be added later). The buffer should be enough for most uses, and others should probably be split into subsets.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com> --- lib/dynamic_debug.c | 16 ++++++++++++---- 1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index d285bb5..6e5b9a3 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -570,24 +570,32 @@ __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 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)) + } + tmpbuf = kmalloc(len + 1, GFP_KERNEL); + if (!tmpbuf) + return -ENOMEM; + if (copy_from_user(tmpbuf, ubuf, len)) { + kfree(tmpbuf); return -EFAULT; + } tmpbuf[len] = '\0'; if (verbose) pr_info("read %d bytes from userspace\n", (int)len); ret = ddebug_exec_query(tmpbuf); + kfree(tmpbuf); if (ret) return ret; -- 1.7.7.3
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