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serial: Move sysrq members above 

At the current place members those follow are:
:	upf_t			flags;
:	upstat_t		status;
:	int			hw_stopped;
:	unsigned int		mctrl;
:	unsigned int		timeout;
:	unsigned int		type;
:	const struct uart_ops	*ops;

Together, they give (*ops) 8-byte align on 64-bit platforms.
And `sysrq_ch` introduces 4-byte padding.

On the other side, above:
:	struct device		*dev;
:	unsigned char		hub6;
:	unsigned char		suspended;
:	unsigned char		unused[2];
:	const char		*name;

Adds another 4-byte padding.

Moving sysrq members just before `hub6` allows to save 8 bytes
per-uart_port on 64-bit platforms:
On my gcc, x86_64 sizeof(struct uart_port) goes from 528 to 520.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-3-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dmitry Safonov 2019-12-13 00:06:01 +00:00 committed by Greg Kroah-Hartman
parent f06327d15a
commit 7e5ed9f5e0
1 changed files with 6 additions and 5 deletions
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11
include/linux/serial_core.h
View File

@ -161,11 +161,6 @@ struct uart_port {
struct uart_icount icount; /* statistics */
struct console *cons; /* struct console, if any */
#if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(SUPPORT_SYSRQ)
unsigned long sysrq; /* sysrq timeout */
unsigned int sysrq_ch; /* char for sysrq */
#endif
/* flags must be updated while holding port mutex */
upf_t flags;
@ -244,6 +239,12 @@ struct uart_port {
resource_size_t mapbase; /* for ioremap */
resource_size_t mapsize;
struct device *dev; /* parent device */
#if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(SUPPORT_SYSRQ)
unsigned long sysrq; /* sysrq timeout */
unsigned int sysrq_ch; /* char for sysrq */
#endif
unsigned char hub6; /* this should be in the 8250 driver */
unsigned char suspended;
unsigned char unused[2];