On 06-11-30 20:57 Daniel Drake wrote: > Stephen Hemminger wrote: > >Why all the trouble do it off work queue? Is someone calling > >set_multicast_list with IRQ's disabled? > > Register I/O involves sleeping, so we need to be in process context. > > in_atomic() returns non-zero in the set_multicast_list handler. I > couldn't tell you which codepath this is in. > > Daniel
The function dev_mc_upload() (net/core/dev_mcast.c) calls netif_tx_lock_bh() which locks the tx spinlock. The ZD1211 is a USB chip. Register reads will always require sleeping, if the driver should not spend CPU cycles on polling in atomic mode. One could implement register writes without waiting for completion of the writes, but asynchronous error messages for the writes would make debugging difficult. Additionally hardware register accesses includes setting a firmware lock, which reqires a register read. Given all that the driver is always sleeping in the register access paths. RX and TX paths don't require register access and work in atomic mode. -- Uli Kunitz - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
