A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? A: No. Q: Should I include quotations after my reply? http://daringfireball.net/2007/07/on_top On Thu, Dec 09, 2021 at 08:15:00AM +0000, wigin zeng wrote: > We encountered this issue when UART transfer very intensive. What issue exactly? > DMA irq-thread processed on CPU0 and serial irq-thread executing on CPU1, > In DMA irq-thread will invoke "tty_insert_filp_string" function to add the rx_buf into tty_buffer. > In serial irq-thread also has chance to access tty_insert_flip_char(in serial8250_rx_chars ) to access tty_buffer. > there is race condition, sometimes will cause panic. But what data is being accessed at the same time to cause a crash? How is data being added into the buffer at the same time in two different places into the same queue? What userspace programs are causing this? > We add the spin_lock to sync the tty_buffer operation, and the issue gone after applied the patch. So all tty buffer accesses need to be protected by your new lock? thanks, greg k-h
