From: Liang Li Date: Sat, 19 Jan 2013 09:52:10 +0000 (+0800) Subject: pch_uart: fix a deadlock when pch_uart as console X-Git-Tag: v3.2.49~6 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=790e332c473eded2396dcf7e2902cbe4429b6a80;p=pandora-kernel.git 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 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed