diff options
Diffstat (limited to 'pcilib/locking.c')
| -rw-r--r-- | pcilib/locking.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/pcilib/locking.c b/pcilib/locking.c index f384ca4..71f204e 100644 --- a/pcilib/locking.c +++ b/pcilib/locking.c @@ -21,10 +21,12 @@ int pcilib_init_locking(pcilib_t* ctx) { pcilib_kmem_reuse_state_t reused; assert(PCILIB_LOCK_PAGES * PCILIB_KMEM_PAGE_SIZE >= PCILIB_MAX_LOCKS * PCILIB_LOCK_SIZE); - + + /*protection against multiple creations of kernel space*/ err = pcilib_lock_global(ctx); if (err) return err; + /* by default, this kernel space is persistent and will be reused, in order to avoid the big initialization times for robust mutexes each time we run pcitool*/ ctx->locks.kmem = pcilib_alloc_kernel_memory(ctx, PCILIB_KMEM_TYPE_PAGE, PCILIB_LOCK_PAGES, PCILIB_KMEM_PAGE_SIZE, 0, PCILIB_KMEM_USE(PCILIB_KMEM_USE_LOCKS,0), PCILIB_KMEM_FLAG_REUSE|PCILIB_KMEM_FLAG_PERSISTENT); if (!ctx->locks.kmem) { pcilib_unlock_global(ctx); @@ -46,6 +48,7 @@ int pcilib_init_locking(pcilib_t* ctx) { } } + /* the lock that has been used for the creation of kernel space is declared unlocked, has we shouldnot use it anymore*/ ctx->locks.locking = pcilib_get_lock(ctx, PCILIB_LOCK_FLAG_UNLOCKED, "locking"); pcilib_unlock_global(ctx); @@ -59,7 +62,7 @@ int pcilib_init_locking(pcilib_t* ctx) { } /* - * this functions destroy all locks and then free the kernel memory allocated for them + * this function free the kernel memory allocated for them and destroys locks by setting memory to 0 */ void pcilib_free_locking(pcilib_t *ctx) { if (ctx->locks.locking) @@ -75,7 +78,7 @@ void pcilib_free_locking(pcilib_t *ctx) { int pcilib_lock_global(pcilib_t *ctx) { int err; - /* we flock() to make sure to not have two initialization in the same time (possible long time to init) */ + /* we flock() on the board's device file to make sure to not have two initialization in the same time (possible long time to init) */ if ((err = flock(ctx->handle, LOCK_EX))==-1) { pcilib_error("Can't get flock on device file"); return PCILIB_ERROR_FAILED; @@ -105,7 +108,7 @@ pcilib_lock_t *pcilib_get_lock(pcilib_t *ctx, pcilib_lock_flags_t flags, const c pcilib_lock_t *lock; char buffer[PCILIB_LOCK_SIZE]; - + /* we construct the complete lock_id given the parameters of the function*/ va_list pa; va_start(pa, lock_id); ret = vsnprintf(buffer, PCILIB_LOCK_SIZE, lock_id, pa); @@ -115,7 +118,9 @@ pcilib_lock_t *pcilib_get_lock(pcilib_t *ctx, pcilib_lock_flags_t flags, const c pcilib_error("Failed to construct the lock id, probably arguments does not match the format string (%s)...", lock_id); return NULL; } - + + + /* we iterate through locks to see if there is one already with the same name*/ // Would be nice to have hash here for (i = 0; i < PCILIB_MAX_LOCKS; i++) { lock = pcilib_get_lock_by_id(ctx, i); @@ -141,6 +146,7 @@ pcilib_lock_t *pcilib_get_lock(pcilib_t *ctx, pcilib_lock_flags_t flags, const c } } #endif /* ! HAVE_STDATOMIC_H */ + /* if yes, we increment its ref variable*/ pcilib_lock_ref(lock); #ifndef HAVE_STDATOMIC_H if ((flags&PCILIB_LOCK_FLAG_UNLOCKED)==0) @@ -192,6 +198,7 @@ pcilib_lock_t *pcilib_get_lock(pcilib_t *ctx, pcilib_lock_flags_t flags, const c return NULL; } + /* if the lock did not exist before, then we create it*/ err = pcilib_init_lock(lock, flags, buffer); if (err) { @@ -229,11 +236,11 @@ void pcilib_return_lock(pcilib_t *ctx, pcilib_lock_flags_t flags, pcilib_lock_t } -/** - * Destroy all existing locks. This is unsafe call as this and other running applications - * will still have all initialized lock pointers. It is user responsibility to issue this - * command when no other application is running. - */ +/* + * Destroy all existing locks. This is unsafe call as this and other running applications + * will still have all initialized lock pointers. It is user responsibility to issue this + * command when no other application is running. + */ int pcilib_destroy_all_locks(pcilib_t *ctx, int force) { int err; pcilib_lock_id_t i; @@ -269,6 +276,7 @@ int pcilib_destroy_all_locks(pcilib_t *ctx, int force) { return 0; } + /* if we run in non-forced case, then if it may be still processes that can have access to the locks, they are not destroyed*/ if (!force) { for (i = 0; i < PCILIB_MAX_LOCKS; i++) { pcilib_lock_t *lock = pcilib_get_lock_by_id(ctx, i); |