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authorLiang Li <liang.li@windriver.com>2013-01-19 17:52:10 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-07-03 11:03:24 -0700
commitdb61e4ec623437237d05b5ab8ce97d9377682de2 (patch)
treeac23384cb73ecfbe95f140b89bd6537658f17ba7 /Makefile
parentc6c46477761504a89d5c68331f3b86fe31b51338 (diff)
pch_uart: fix a deadlock when pch_uart as console
commit 384e301e3519599b000c1a2ecd938b533fc15d85 upstream. When we use pch_uart as system console like 'console=ttyPCH0,115200', then 'send break' to it. We'll encounter the deadlock on a cpu/core, with interrupts disabled on the core. When we happen to have all irqs affinity to cpu0 then the deadlock on cpu0 actually deadlock whole system. In pch_uart_interrupt, we have spin_lock_irqsave(&priv->lock, flags) then call pch_uart_err_ir when break is received. Then the call to dev_err would actually call to pch_console_write then we'll run into another spin_lock(&priv->lock), with interrupts disabled. So in the call sequence lead by pch_uart_interrupt, we should be carefully to call functions that will 'print message to console' only in case the uart port is not being used as serial console. Signed-off-by: Liang Li <liang.li@windriver.com> Cc: Yijing Wang <wangyijing@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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