minix/servers/vfs/glo.h
David van Moolenbroek 723e51327f VFS: worker thread model overhaul
The main purpose of this patch is to fix handling of unpause calls
from PM while another call is ongoing. The solution to this problem
sparked a full revision of the threading model, consisting of a large
number of related changes:

- all active worker threads are now always associated with a process,
  and every process has at most one active thread working for it;
- the process lock is always held by a process's worker thread;
- a process can now have both normal work and postponed PM work
  associated to it;
- timer expiry and non-postponed PM work is done from the main thread;
- filp garbage collection is done from a thread associated with VFS;
- reboot calls from PM are now done from a thread associated with PM;
- the DS events handler is protected from starting multiple threads;
- support for a system worker thread has been removed;
- the deadlock recovery thread has been replaced by a parameter to the
  worker_start() function; the number of worker threads has
  consequently been increased by one;
- saving and restoring of global but per-thread variables is now
  centralized in worker_suspend() and worker_resume(); err_code is now
  saved and restored in all cases;
- the concept of jobs has been removed, and job_m_in now points to a
  message stored in the worker thread structure instead;
- the PM lock has been removed;
- the separate exec lock has been replaced by a lock on the VM
  process, which was already being locked for exec calls anyway;
- PM_UNPAUSE is now processed as a postponed PM request, from a thread
  associated with the target process;
- the FP_DROP_WORK flag has been removed, since it is no longer more
  than just an optimization and only applied to processes operating on
  a pipe when getting killed;
- assignment to "fp" now takes place only when obtaining new work in
  the main thread or a worker thread, when resuming execution of a
  thread, and in the special case of exiting processes during reboot;
- there are no longer special cases where the yield() call is used to
  force a thread to run.

Change-Id: I7a97b9b95c2450454a9b5318dfa0e6150d4e6858
2014-02-18 11:25:03 +01:00

50 lines
1.7 KiB
C

#ifndef __VFS_GLO_H__
#define __VFS_GLO_H__
/* EXTERN should be extern except for the table file */
#ifdef _TABLE
#undef EXTERN
#define EXTERN
#endif
#include <minix/param.h>
/* File System global variables */
EXTERN struct fproc *fp; /* pointer to caller's fproc struct */
EXTERN int susp_count; /* number of procs suspended on pipe */
EXTERN int nr_locks; /* number of locks currently in place */
EXTERN int reviving; /* number of pipe processes to be revived */
EXTERN int pending;
EXTERN int sending;
EXTERN int verbose;
EXTERN dev_t ROOT_DEV; /* device number of the root device */
EXTERN int ROOT_FS_E; /* kernel endpoint of the root FS proc */
EXTERN u32_t system_hz; /* system clock frequency. */
/* The parameters of the call are kept here. */
EXTERN message m_in; /* the input message itself */
# define who_p ((int) (fp - fproc))
# define fproc_addr(e) (&fproc[_ENDPOINT_P(e)])
# define who_e (self != NULL ? fp->fp_endpoint : m_in.m_source)
# define call_nr (m_in.m_type)
# define job_m_in (self->w_msg)
# define job_call_nr (job_m_in.m_type)
# define super_user (fp->fp_effuid == SU_UID ? 1 : 0)
# define scratch(p) (scratchpad[((int) ((p) - fproc))])
EXTERN struct worker_thread *self;
EXTERN int deadlock_resolving;
EXTERN mutex_t bsf_lock;/* Global lock for access to block special files */
EXTERN struct worker_thread workers[NR_WTHREADS];
EXTERN char mount_label[LABEL_MAX]; /* label of file system to mount */
/* The following variables are used for returning results to the caller. */
EXTERN int err_code; /* temporary storage for error number */
/* Data initialized elsewhere. */
extern int(*call_vec[]) (message *);
extern int(*pfs_call_vec[]) (message *m_out);
EXTERN struct kinfo kinfo; /* kernel information */
#endif