On Monday 11 of July 2011 22:11:48 Jean Delvare wrote: > > spi_sync call uses its spi_message parameter to keep completion > > information, having this structure static is not thread-safe, > > potentially causing one thread having pointers to memory on or above > > other threads stack. use mutex to prevent multiple access > > This has nothing to do with static, as a matter of fact the structure > is dynamically allocated. The bottom line is that the driver structure > is such that calls to max1111_read() must be serialized.
the structure is dynamically allocated, but the pointer used to hold it is a static global var. "static" in this context meant "shared by all threads" > > + /* spi_sync requires data not to be freed before function returns > > + * for static data, any access is dangerous, use locks > > + */ > > This has nothing to do with "freeing data". max1111_read() doesn't free > anything. It is making use of a data structure, the access to which > must be serialized. Easy as that. And no, access isn't dangerous ;) as spi_message contains a pointer to completion (created and waited on by spi_sync()), witch gets rewritten and causes the NULL exception, writing to it while the call is in progress is bad idea. also changing the message sent half-way would not be very nice. reading would be fine, though > Please respin your patch with a better struct member name and improved > description and comments, and I'll be happy to apply it. on it _______________________________________________ Zaurus-devel mailing list Zaurus-devel@lists.linuxtogo.org http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/zaurus-devel
