kmsg: add predefined _PID, _TID, _COMM keywords to kmsg* log dict

kmsg* devices write operation wrote no dict along with message
Due to usage of kmsg devices in userspace dict has been added
identifying pid, tid and comm of writing process.

Signed-off-by: Marcin Niesluchowski <m.niesluchow@samsung.com>
Change-Id: Idead2fa29607785031e37542c2f48481b04f9949

diff --git a/kernel/printk_kmsg.c b/kernel/printk_kmsg.c
index 09a2ee5..5b2afd9 100644 (file)
--- a/kernel/printk_kmsg.c
+++ b/kernel/printk_kmsg.c
@@ -854,7 +854,34 @@ void log_buf_release(struct kref *ref)
        kfree(log_b);
 }
 
-static int kmsg_sys_write(int minor, int level, const char *fmt, ...)
+#define MAX_PID_LEN    20
+#define MAX_TID_LEN    20
+/*
+ * Fromat below describes dict appended to message written from userspace:
+ * "_PID=<pid>\0_TID=<tid>\0_COMM=<comm>"
+ * KMSG_DICT_MAX_LEN definition represents maximal length of this dict.
+ */
+#define KMSG_DICT_MAX_LEN      (5 + MAX_PID_LEN + 1 + \
+                                5 + MAX_TID_LEN + 1 + \
+                                6 + TASK_COMM_LEN)
+
+static size_t set_kmsg_dict(char *buf)
+{
+       size_t len;
+
+       len = sprintf(buf, "_PID=%d", task_tgid_nr(current)) + 1;
+       len += sprintf(buf + len, "_TID=%d", task_pid_nr(current)) + 1;
+       memcpy(buf + len, "_COMM=", 6);
+       len += 6;
+       get_task_comm(buf + len, current);
+       while (buf[len] != '\0')
+               len++;
+       return len;
+}
+
+static int kmsg_sys_write(int minor, int level,
+                         const char *dict, size_t dictlen,
+                         const char *fmt, ...)
 {
        va_list args;
        int ret = -ENXIO;
@@ -869,7 +896,7 @@ static int kmsg_sys_write(int minor, int level, const char *fmt, ...)
 
                va_start(args, fmt);
                log_format_and_store(log_b, 1 /* LOG_USER */, level,
-                                    NULL, 0, fmt, smp_processor_id(), args);
+                                    dict, dictlen, fmt, smp_processor_id(), args);
                va_end(args);
                wake_up_interruptible(&log_b->wait);
 
@@ -890,6 +917,8 @@ static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
        int level = default_message_loglevel;
        int facility = 1;       /* LOG_USER */
        size_t len = iov_length(iv, count);
+       char dict[KMSG_DICT_MAX_LEN];
+       size_t dictlen;
        ssize_t ret = len;
        int minor = iminor(iocb->ki_filp->f_inode);
 
@@ -933,10 +962,12 @@ static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
        }
        line[len] = '\0';
 
+       dictlen = set_kmsg_dict(dict);
+
        if (minor == log_buf.minor) {
-               printk_emit(facility, level, NULL, 0, "%s", line);
+               printk_emit(facility, level, dict, dictlen, "%s", line);
        } else {
-               int error = kmsg_sys_write(minor, level, NULL, 0, "%s", line);
+               int error = kmsg_sys_write(minor, level, dict, dictlen, "%s", line);
 
                if (error)
                        ret = error;