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serial: cpm_uart: Avoid suspicious locking

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[ Upstream commit 36ef11d311f405e55ad8e848c19b212ff71ef536 ]

  CHECK   drivers/tty/serial/cpm_uart/cpm_uart_core.c
drivers/tty/serial/cpm_uart/cpm_uart_core.c:1271:39: warning: context imbalance in 'cpm_uart_console_write' - unexpected unlock

Allthough 'nolock' is not expected to change, sparse find the following
form suspicious:

	if (unlikely(nolock)) {
		local_irq_save(flags);
	} else {
		spin_lock_irqsave(&pinfo->port.lock, flags);
	}

	cpm_uart_early_write(pinfo, s, count, true);

	if (unlikely(nolock)) {
		local_irq_restore(flags);
	} else {
		spin_unlock_irqrestore(&pinfo->port.lock, flags);
	}

Rewrite it a more obvious form:

	if (unlikely(oops_in_progress)) {
		local_irq_save(flags);
		cpm_uart_early_write(pinfo, s, count, true);
		local_irq_restore(flags);
	} else {
		spin_lock_irqsave(&pinfo->port.lock, flags);
		cpm_uart_early_write(pinfo, s, count, true);
		spin_unlock_irqrestore(&pinfo->port.lock, flags);
	}

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/f7da5cdc9287960185829cfef681a7d8614efa1f.1691068700.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Christophe Leroy 2023-08-03 15:56:42 +02:00 committed by Greg Kroah-Hartman
parent 4738bf8b2d
commit a3c9315a8c
1 changed files with 4 additions and 9 deletions
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13
drivers/tty/serial/cpm_uart/cpm_uart_core.c
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@ -1257,19 +1257,14 @@ static void cpm_uart_console_write(struct console *co, const char *s,
{
struct uart_cpm_port *pinfo = &cpm_uart_ports[co->index];
unsigned long flags;
int nolock = oops_in_progress;
if (unlikely(nolock)) {
if (unlikely(oops_in_progress)) {
local_irq_save(flags);
} else {
spin_lock_irqsave(&pinfo->port.lock, flags);
}
cpm_uart_early_write(pinfo, s, count, true);
if (unlikely(nolock)) {
cpm_uart_early_write(pinfo, s, count, true);
local_irq_restore(flags);
} else {
spin_lock_irqsave(&pinfo->port.lock, flags);
cpm_uart_early_write(pinfo, s, count, true);
spin_unlock_irqrestore(&pinfo->port.lock, flags);
}
}