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| author | Johan Hovold <johan@kernel.org> | 2021-07-14 10:04:27 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-21 12:53:26 +0200 |
| commit | 853a9ae29e978d37f5dfa72622a68c9ae3d7fa89 (patch) | |
| tree | c3f2b62c6447e6b7fae006107281233aa99dfcce /include/linux/serial_core.h | |
| parent | cc9ca4d95846cbbece48d9cd385550f8fba6a3c1 (diff) | |
| download | linux-853a9ae29e978d37f5dfa72622a68c9ae3d7fa89.tar.gz linux-853a9ae29e978d37f5dfa72622a68c9ae3d7fa89.tar.bz2 linux-853a9ae29e978d37f5dfa72622a68c9ae3d7fa89.zip | |
serial: 8250: fix handle_irq locking
The 8250 handle_irq callback is not just called from the interrupt
handler but also from a timer callback when polling (e.g. for ports
without an interrupt line). Consequently the callback must explicitly
disable interrupts to avoid a potential deadlock with another interrupt
in polled mode.
Add back an irqrestore-version of the sysrq port-unlock helper and use
it in the 8250 callbacks that need it.
Fixes: 75f4e830fa9c ("serial: do not restore interrupt state in sysrq helper")
Cc: stable@vger.kernel.org # 5.13
Cc: Joel Stanley <joel@jms.id.au>
Cc: Andrew Jeffery <andrew@aj.id.au>
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210714080427.28164-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/serial_core.h')
| -rw-r--r-- | include/linux/serial_core.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 52d7fb92a69d..c58cc142d23f 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -518,6 +518,25 @@ static inline void uart_unlock_and_check_sysrq(struct uart_port *port) if (sysrq_ch) handle_sysrq(sysrq_ch); } + +static inline void uart_unlock_and_check_sysrq_irqrestore(struct uart_port *port, + unsigned long flags) +{ + int sysrq_ch; + + if (!port->has_sysrq) { + spin_unlock_irqrestore(&port->lock, flags); + return; + } + + sysrq_ch = port->sysrq_ch; + port->sysrq_ch = 0; + + spin_unlock_irqrestore(&port->lock, flags); + + if (sysrq_ch) + handle_sysrq(sysrq_ch); +} #else /* CONFIG_MAGIC_SYSRQ_SERIAL */ static inline int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch) { @@ -531,6 +550,11 @@ static inline void uart_unlock_and_check_sysrq(struct uart_port *port) { spin_unlock(&port->lock); } +static inline void uart_unlock_and_check_sysrq_irqrestore(struct uart_port *port, + unsigned long flags) +{ + spin_unlock_irqrestore(&port->lock, flags); +} #endif /* CONFIG_MAGIC_SYSRQ_SERIAL */ /* |