I searching for a kind of mutex which also blocks a specific DSRs.
Mutexes
doesn't work within DSRs, so the only way to share resources which are
used
by a thread and a DSR is to use scheduler_lock() which blocks the whole
system.
Take a look at
http://ecos.sourceware.org/docs-latest/ref/devapi-synchronization.html
It suggests to use cyg_drv_dsr_lock()/cyg_drv_dsr_unlock(). This
should, it think, leave the scheduler running. However, in RTOSs, most
things are triggered by ISR, which naturally post DSR, and if you have
DSRs locked, events are just going to get queued up and never actually
processed. So think about deadlocks, try not to make any blocking
calls while you have DSR locked etc...
Take a look at the serial device driver layers for examples of how to
use these locks.