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c3cce2e67b
uart_handle_break() and uart_prepare_sysrq_char() (in include/linux/serial_core.h) capture a SysRq character into port->sysrq_ch while the port lock is held and rely on the unlock helper -- uart_unlock_and_check_sysrq_irqrestore() -- to dispatch the captured character to handle_sysrq() on scope exit. The existing guard(uart_port_lock_irqsave) cannot be used by IRQ handlers that process RX, because its destructor calls plain uart_port_unlock_irqrestore() and silently drops port->sysrq_ch. Add a dedicated guard(uart_port_lock_check_sysrq_irqsave) variant whose destructor is the sysrq-aware unlock helper. The lock side is identical to uart_port_lock_irqsave -- only the unlock-time behaviour differs. Callers that may capture SysRq characters must use guard(uart_port_lock_check_sysrq_irqsave); the existing guard(uart_port_lock_irqsave) keeps its current plain-unlock semantics for the many callers that do not process RX. The new macro is placed after the CONFIG_MAGIC_SYSRQ_SERIAL block so both definitions of uart_unlock_and_check_sysrq_irqrestore() (sysrq enabled and disabled) are visible at expansion time. When CONFIG_MAGIC_SYSRQ_SERIAL=n the destructor degenerates to plain uart_port_unlock_irqrestore(), so there is no overhead. No functional change on its own; users are converted in the following patches. Cc: stable@vger.kernel.org Signed-off-by: Jacques Nilo <jnilo@free.fr> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/3849af4bc55d5d2a424fa850844e94d641b2f8a6.1778675349.git.jnilo@free.fr Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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