5.1-RELEASE TODO

[John Baldwin]

On 19-May-2003 Robert Watson wrote:
> 
> On Mon, 19 May 2003, Terry Lambert wrote:
> 
>> Robert Watson wrote:
>> >    |-------------------+-------------+---------------+----------------------|
>> >    |                   |             |               | Update the run-time  |
>> >    | rtld-elf          | --          | Alexander     | link editor (rtld)   |
>> >    | thread-safety     |             | Kabaev        | thread-safe with     |
>> >    |                   |             |               | libpthread.          |
>> >    |-------------------+-------------+---------------+----------------------|
>> 
>> According to chapter 12 of the "Go Solo 2" book, this is a bogus thing
>> to do.  Callers are required to take a critical section over the calls
>> to the dl* functions because the dlerror() function uses a static buffer
>> that can be overwritten in a multi-threaded environment. 
> 
> Sadly, that insight doesn't seem to have influenced the development
> practices of a number of major application vendors :-(. 

As Peter has mentioned before, simply locking calls to dlopen() in the
application is not sufficient since every time you have to resolve a
symbol when doing a call to a function for the first time, you hit the
same data structures and need the locks in those cases as well.  Assuming
I recalled all that correctly.

-- 

John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/