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>
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@ -266,6 +266,7 @@ static struct console *exclusive_console;
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#define MAX_CMDLINECONSOLES 8
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static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
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static int console_cmdline_cnt;
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static int preferred_console = -1;
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int console_set_on_cmdline;
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@ -1902,12 +1903,25 @@ static int __add_preferred_console(char *name, int idx, char *options,
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* See if this tty is not yet registered, and
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* if we have a slot free.
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*/
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for (i = 0, c = console_cmdline;
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i < MAX_CMDLINECONSOLES && c->name[0];
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i++, c++) {
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for (i = 0, c = console_cmdline; i < console_cmdline_cnt; i++, c++) {
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if (strcmp(c->name, name) == 0 && c->index == idx) {
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if (!brl_options)
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preferred_console = i;
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if (brl_options)
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return 0;
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/*
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* Maintain an invariant that will help to find if
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* the matching console is preferred, see
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* register_console():
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*
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* The last non-braille console is always
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* the preferred one.
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*/
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if (i != console_cmdline_cnt - 1)
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swap(console_cmdline[i],
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console_cmdline[console_cmdline_cnt - 1]);
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preferred_console = console_cmdline_cnt - 1;
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return 0;
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}
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}
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@ -1920,6 +1934,7 @@ static int __add_preferred_console(char *name, int idx, char *options,
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braille_set_options(c, brl_options);
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c->index = idx;
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console_cmdline_cnt++;
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return 0;
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}
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/*
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@ -2459,12 +2474,23 @@ void register_console(struct console *newcon)
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}
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/*
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* See if this console matches one we selected on
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* the command line.
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* See if this console matches one we selected on the command line.
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*
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* There may be several entries in the console_cmdline array matching
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* with the same console, one with newcon->match(), another by
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* name/index:
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*
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* pl011,mmio,0x87e024000000,115200 -- added from SPCR
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* ttyAMA0 -- added from command line
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*
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* Traverse the console_cmdline array in reverse order to be
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* sure that if this console is preferred then it will be the first
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* matching entry. We use the invariant that is maintained in
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* __add_preferred_console().
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*/
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for (i = 0, c = console_cmdline;
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i < MAX_CMDLINECONSOLES && c->name[0];
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i++, c++) {
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for (i = console_cmdline_cnt - 1; i >= 0; i--) {
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c = console_cmdline + i;
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if (!newcon->match ||
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newcon->match(newcon, c->name, c->index, c->options) != 0) {
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/* default matching */
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