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authorAleksey Makarov <aleksey.makarov@linaro.org>2017-04-05 23:20:00 +0300
committerPetr Mladek <pmladek@suse.com>2017-04-12 11:40:22 +0200
commitcf39bf58afdaabc0b86f141630fb3fd18190294e (patch)
tree299a204a7447f5c84cdd1de0588b5e892c117cdd /kernel/printk
parentad86ee2b8a47590f62a4f3bc1d25dc126d121cb9 (diff)
downloadlinux-cf39bf58afdaabc0b86f141630fb3fd18190294e.tar.bz2
printk: fix double printing with earlycon
If a console was specified by ACPI SPCR table _and_ command line parameters like "console=ttyAMA0" _and_ "earlycon" were specified, then log messages appear twice. The root cause is that the code traverses the list of specified consoles (the `console_cmdline` array) and stops at the first match. But it may happen that the same console is referred by the elements of this array twice: pl011,mmio,0x87e024000000,115200 -- from SPCR ttyAMA0 -- from command line but in this case `preferred_console` points to the second entry and the flag CON_CONSDEV is not set, so bootconsole is not deregistered. To fix that, introduce an invariant "The last non-braille console is always the preferred one" on the entries of the console_cmdline array. Then traverse it in reverse order to be sure that if the console is preferred then it will be the first matching entry. Introduce variable console_cmdline_cnt that keeps the number of elements of the console_cmdline array (Petr Mladek). It helps to get rid of the loop that searches for the end of this array. Link: http://lkml.kernel.org/r/20170405202006.18234-1-aleksey.makarov@linaro.org Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: "Nair, Jayachandran" <Jayachandran.Nair@cavium.com> Cc: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org> Reported-by: Sudeep Holla <sudeep.holla@arm.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
Diffstat (limited to 'kernel/printk')
-rw-r--r--kernel/printk/printk.c46
1 files changed, 36 insertions, 10 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 82927ca04849..06051926dfde 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -266,6 +266,7 @@ static struct console *exclusive_console;
#define MAX_CMDLINECONSOLES 8
static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
+static int console_cmdline_cnt;
static int preferred_console = -1;
int console_set_on_cmdline;
@@ -1902,12 +1903,25 @@ static int __add_preferred_console(char *name, int idx, char *options,
* See if this tty is not yet registered, and
* if we have a slot free.
*/
- for (i = 0, c = console_cmdline;
- i < MAX_CMDLINECONSOLES && c->name[0];
- i++, c++) {
+ for (i = 0, c = console_cmdline; i < console_cmdline_cnt; i++, c++) {
if (strcmp(c->name, name) == 0 && c->index == idx) {
- if (!brl_options)
- preferred_console = i;
+ if (brl_options)
+ return 0;
+
+ /*
+ * Maintain an invariant that will help to find if
+ * the matching console is preferred, see
+ * register_console():
+ *
+ * The last non-braille console is always
+ * the preferred one.
+ */
+ if (i != console_cmdline_cnt - 1)
+ swap(console_cmdline[i],
+ console_cmdline[console_cmdline_cnt - 1]);
+
+ preferred_console = console_cmdline_cnt - 1;
+
return 0;
}
}
@@ -1920,6 +1934,7 @@ static int __add_preferred_console(char *name, int idx, char *options,
braille_set_options(c, brl_options);
c->index = idx;
+ console_cmdline_cnt++;
return 0;
}
/*
@@ -2459,12 +2474,23 @@ void register_console(struct console *newcon)
}
/*
- * See if this console matches one we selected on
- * the command line.
+ * See if this console matches one we selected on the command line.
+ *
+ * There may be several entries in the console_cmdline array matching
+ * with the same console, one with newcon->match(), another by
+ * name/index:
+ *
+ * pl011,mmio,0x87e024000000,115200 -- added from SPCR
+ * ttyAMA0 -- added from command line
+ *
+ * Traverse the console_cmdline array in reverse order to be
+ * sure that if this console is preferred then it will be the first
+ * matching entry. We use the invariant that is maintained in
+ * __add_preferred_console().
*/
- for (i = 0, c = console_cmdline;
- i < MAX_CMDLINECONSOLES && c->name[0];
- i++, c++) {
+ for (i = console_cmdline_cnt - 1; i >= 0; i--) {
+ c = console_cmdline + i;
+
if (!newcon->match ||
newcon->match(newcon, c->name, c->index, c->options) != 0) {
/* default matching */