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authorJohan Hovold <johan@kernel.org>2021-07-14 11:04:27 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-07-21 13:53:26 +0300
commit853a9ae29e978d37f5dfa72622a68c9ae3d7fa89 (patch)
treec3f2b62c6447e6b7fae006107281233aa99dfcce /include
parentcc9ca4d95846cbbece48d9cd385550f8fba6a3c1 (diff)
downloadlinux-853a9ae29e978d37f5dfa72622a68c9ae3d7fa89.tar.xz
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')
-rw-r--r--include/linux/serial_core.h24
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 */
/*