X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fjournal%2Fmmap-cache.c;h=4c940aaa24afb9a3a7f6371f8c5ce5fb146eeea2;hp=7dbbb5ef381b4c6b617441c4a6dae2c74aae9ca3;hb=69adae5168da231c6cf319f708860954701b25ed;hpb=ae97089d49d1795a35a443b7b830ee666028e733 diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c index 7dbbb5ef3..4c940aaa2 100644 --- a/src/journal/mmap-cache.c +++ b/src/journal/mmap-cache.c @@ -38,7 +38,7 @@ typedef struct FileDescriptor FileDescriptor; struct Window { MMapCache *cache; - unsigned keep_always; + bool keep_always; bool in_unused; int prot; @@ -76,14 +76,20 @@ struct MMapCache { Hashmap *fds; - Hashmap *contexts; + Context *contexts[MMAP_CACHE_MAX_CONTEXTS]; LIST_HEAD(Window, unused); Window *last_unused; }; #define WINDOWS_MIN 64 -#define WINDOW_SIZE (8ULL*1024ULL*1024ULL) + +#ifdef ENABLE_DEBUG_MMAP_CACHE +/* Tiny windows increase mmap activity and the chance of exposing unsafe use. */ +# define WINDOW_SIZE (page_size()) +#else +# define WINDOW_SIZE (8ULL*1024ULL*1024ULL) +#endif MMapCache* mmap_cache_new(void) { MMapCache *m; @@ -185,13 +191,19 @@ static void context_detach_window(Context *c) { c->window = NULL; LIST_REMOVE(by_window, w->contexts, c); - if (!w->contexts && w->keep_always == 0) { + if (!w->contexts && !w->keep_always) { /* Not used anymore? */ +#ifdef ENABLE_DEBUG_MMAP_CACHE + /* Unmap unused windows immediately to expose use-after-unmap + * by SIGSEGV. */ + window_free(w); +#else LIST_PREPEND(unused, c->cache->unused, w); if (!c->cache->last_unused) c->cache->last_unused = w; w->in_unused = true; +#endif } } @@ -219,18 +231,13 @@ static void context_attach_window(Context *c, Window *w) { static Context *context_add(MMapCache *m, unsigned id) { Context *c; - int r; assert(m); - c = hashmap_get(m->contexts, UINT_TO_PTR(id + 1)); + c = m->contexts[id]; if (c) return c; - r = hashmap_ensure_allocated(&m->contexts, trivial_hash_func, trivial_compare_func); - if (r < 0) - return NULL; - c = new0(Context, 1); if (!c) return NULL; @@ -238,11 +245,8 @@ static Context *context_add(MMapCache *m, unsigned id) { c->cache = m; c->id = id; - r = hashmap_put(m->contexts, UINT_TO_PTR(id + 1), c); - if (r < 0) { - free(c); - return NULL; - } + assert(!m->contexts[id]); + m->contexts[id] = c; return c; } @@ -252,8 +256,10 @@ static void context_free(Context *c) { context_detach_window(c); - if (c->cache) - assert_se(hashmap_remove(c->cache->contexts, UINT_TO_PTR(c->id + 1))); + if (c->cache) { + assert(c->cache->contexts[c->id] == c); + c->cache->contexts[c->id] = NULL; + } free(c); } @@ -281,7 +287,7 @@ static FileDescriptor* fd_add(MMapCache *m, int fd) { if (f) return f; - r = hashmap_ensure_allocated(&m->fds, trivial_hash_func, trivial_compare_func); + r = hashmap_ensure_allocated(&m->fds, NULL); if (r < 0) return NULL; @@ -302,15 +308,14 @@ static FileDescriptor* fd_add(MMapCache *m, int fd) { } static void mmap_cache_free(MMapCache *m) { - Context *c; FileDescriptor *f; + int i; assert(m); - while ((c = hashmap_first(m->contexts))) - context_free(c); - - hashmap_free(m->contexts); + for (i = 0; i < MMAP_CACHE_MAX_CONTEXTS; i++) + if (m->contexts[i]) + context_free(m->contexts[i]); while ((f = hashmap_first(m->fds))) fd_free(f); @@ -360,8 +365,9 @@ static int try_context( assert(m->n_ref > 0); assert(fd >= 0); assert(size > 0); + assert(ret); - c = hashmap_get(m->contexts, UINT_TO_PTR(context+1)); + c = m->contexts[context]; if (!c) return 0; @@ -377,10 +383,9 @@ static int try_context( return 0; } - c->window->keep_always += keep_always; + c->window->keep_always |= keep_always; - if (ret) - *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset); + *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset); return 1; } @@ -423,8 +428,7 @@ static int find_mmap( context_attach_window(c, w); w->keep_always += keep_always; - if (ret) - *ret = (uint8_t*) w->ptr + (offset - w->offset); + *ret = (uint8_t*) w->ptr + (offset - w->offset); return 1; } @@ -450,6 +454,7 @@ static int add_mmap( assert(m->n_ref > 0); assert(fd >= 0); assert(size > 0); + assert(ret); woffset = offset & ~((uint64_t) page_size() - 1ULL); wsize = size + (offset - woffset); @@ -496,15 +501,15 @@ static int add_mmap( c = context_add(m, context); if (!c) - return -ENOMEM; + goto outofmem; f = fd_add(m, fd); if (!f) - return -ENOMEM; + goto outofmem; w = window_add(m); if (!w) - return -ENOMEM; + goto outofmem; w->keep_always = keep_always; w->ptr = d; @@ -519,9 +524,12 @@ static int add_mmap( c->window = w; LIST_PREPEND(by_window, w->contexts, c); - if (ret) - *ret = (uint8_t*) w->ptr + (offset - w->offset); + *ret = (uint8_t*) w->ptr + (offset - w->offset); return 1; + +outofmem: + munmap(d, wsize); + return -ENOMEM; } int mmap_cache_get( @@ -541,6 +549,8 @@ int mmap_cache_get( assert(m->n_ref > 0); assert(fd >= 0); assert(size > 0); + assert(ret); + assert(context < MMAP_CACHE_MAX_CONTEXTS); /* Check whether the current context is the right one already */ r = try_context(m, fd, prot, context, keep_always, offset, size, ret); @@ -562,42 +572,6 @@ int mmap_cache_get( return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret); } -int mmap_cache_release( - MMapCache *m, - int fd, - int prot, - unsigned context, - uint64_t offset, - size_t size) { - - FileDescriptor *f; - Window *w; - - assert(m); - assert(m->n_ref > 0); - assert(fd >= 0); - assert(size > 0); - - f = hashmap_get(m->fds, INT_TO_PTR(fd + 1)); - if (!f) - return -EBADF; - - assert(f->fd == fd); - - LIST_FOREACH(by_fd, w, f->windows) - if (window_matches(w, fd, prot, offset, size)) - break; - - if (!w) - return -ENOENT; - - if (w->keep_always == 0) - return -ENOLCK; - - w->keep_always -= 1; - return 0; -} - void mmap_cache_close_fd(MMapCache *m, int fd) { FileDescriptor *f; @@ -611,18 +585,6 @@ void mmap_cache_close_fd(MMapCache *m, int fd) { fd_free(f); } -void mmap_cache_close_context(MMapCache *m, unsigned context) { - Context *c; - - assert(m); - - c = hashmap_get(m->contexts, UINT_TO_PTR(context + 1)); - if (!c) - return; - - context_free(c); -} - unsigned mmap_cache_get_hit(MMapCache *m) { assert(m);