accel-ppp.git/accel-pppd/triton, branch 1.12

triton: fix context schedule/wakeup race

2018-11-03T06:00:11+00:00

Allow triton_context_wakeup() to run before triton_context_schedule(). When that happens, triton_context_schedule() now lets the context running instead of putting it in sleep mode. Note that, even though triton now allows triton_context_wakeup() to happen before triton_context_schedule(), these two functions still need to be paired and not nested. That is, in a sequence like the following, triton_context_wakeup() triton_context_wakeup() triton_context_schedule() triton_context_schedule() the second triton_context_schedule() would put the context in sleep mode. No matter how many triton_context_wakeup() have been called, the first triton_context_schedule() "consumes" them all. Being immune to schedule/wakeup inversion allows to fix the pppd_compat module. This module needs to fork() to execute external programs. The parent then waits for completion of its child using triton_context_schedule(). When child terminates, the sigchld module runs a callback that has to call triton_context_wakeup() to resume execution of the parent. The problem is that there is no synchronisation between the parent and its child. When under stress, the child may execute faster than its parent and the sigchld callback might run triton_context_wakeup() before the parent had time to call triton_context_schedule(). Then accel-ppp might crash because the triton thread might have reset ctx->thread to NULL, making triton_context_wakeup() write to invalid memory when trying to insert the context in ctx->thread->wakeup_list[]. Synchronising the parent and its child completion's callback would require cooperation from triton_context_schedule(). Otherwise we would still have a time frame between the moment we let the callback waking up the context and the moment we put the context in sleep mode. Allowing schedule/wakeup call inversion in triton looks simpler since it avoids modifying the current API. Signed-off-by: Guillaume Nault

triton: make mempool.h self-contained even when MEMDEBUG is defined

2018-10-26T03:34:34+00:00

If MEMDEBUG is defined, then we need to include "memdebug.h" to define 'md_free'. Signed-off-by: Guillaume Nault

triton: fixed improper locking

2018-05-28T14:18:04+00:00

triton: prevent alloc_context function to be inlined (fixes improper stack size calculation)

2018-03-06T09:11:37+00:00

fix build error with VALGRIND defined

2018-03-03T21:42:02+00:00

triton: more general fix of thread wake up crash

2018-03-02T14:43:38+00:00

after commit 287adbfc205c02eac375f55fb94f13c073faec97 gcc still may reorder alloca() and memset() calls. fix that with volatile access & memory barrier.

triton: fix crash due gcc mis-optimization of alloca()

2017-12-27T21:27:07+00:00

since alloca() result is used indirectly, gcc 4.7.2 thinks the whole call can be dropped on any optimization level.

triton: fixed bugs introduced by previous commit

2017-12-27T08:43:09+00:00

reworked context priorities

2017-12-26T17:46:06+00:00

Introduced 4 priorities: 0 - management (cli) 1 - starting sessions (default priority) 2 - active sessions 3 - finishing sessions

triton: rewrited context sleeping implementation

2017-10-12T15:47:12+00:00

Instead of entering working thread into sleep triton saves machine context and stack on sleep and restores context/stack on wakeup. This saves costly new thread allocation.