diff options
Diffstat (limited to 'kernel/power')
| -rw-r--r-- | kernel/power/power.h | 64 | ||||
| -rw-r--r-- | kernel/power/snapshot.c | 40 |
2 files changed, 76 insertions, 28 deletions
diff --git a/kernel/power/power.h b/kernel/power/power.h index 59ce712f082..1cefcf87a69 100644 --- a/kernel/power/power.h +++ b/kernel/power/power.h @@ -50,17 +50,65 @@ extern asmlinkage int swsusp_arch_resume(void); extern unsigned int count_data_pages(void); +/** + * Auxiliary structure used for reading the snapshot image data and + * metadata from and writing them to the list of page backup entries + * (PBEs) which is the main data structure of swsusp. + * + * Using struct snapshot_handle we can transfer the image, including its + * metadata, as a continuous sequence of bytes with the help of + * snapshot_read_next() and snapshot_write_next(). + * + * The code that writes the image to a storage or transfers it to + * the user land is required to use snapshot_read_next() for this + * purpose and it should not make any assumptions regarding the internal + * structure of the image. Similarly, the code that reads the image from + * a storage or transfers it from the user land is required to use + * snapshot_write_next(). + * + * This may allow us to change the internal structure of the image + * in the future with considerably less effort. + */ + struct snapshot_handle { - loff_t offset; - unsigned int page; - unsigned int page_offset; - unsigned int prev; - struct pbe *pbe, *last_pbe; - void *buffer; - unsigned int buf_offset; - int sync_read; + loff_t offset; /* number of the last byte ready for reading + * or writing in the sequence + */ + unsigned int cur; /* number of the block of PAGE_SIZE bytes the + * next operation will refer to (ie. current) + */ + unsigned int cur_offset; /* offset with respect to the current + * block (for the next operation) + */ + unsigned int prev; /* number of the block of PAGE_SIZE bytes that + * was the current one previously + */ + struct pbe *pbe; /* PBE that corresponds to 'buffer' */ + struct pbe *last_pbe; /* When the image is restored (eg. read + * from disk) we can store some image + * data directly in the page frames + * in which they were before suspend. + * In such a case the PBEs that + * correspond to them will be unused. + * This is the last PBE, so far, that + * does not correspond to such data. + */ + void *buffer; /* address of the block to read from + * or write to + */ + unsigned int buf_offset; /* location to read from or write to, + * given as a displacement from 'buffer' + */ + int sync_read; /* Set to one to notify the caller of + * snapshot_write_next() that it may + * need to call wait_on_bio_chain() + */ }; +/* This macro returns the address from/to which the caller of + * snapshot_read_next()/snapshot_write_next() is allowed to + * read/write data after the function returns + */ #define data_of(handle) ((handle).buffer + (handle).buf_offset) extern int snapshot_read_next(struct snapshot_handle *handle, size_t count); diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 979096c2777..81fe8de9e60 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -555,7 +555,7 @@ static inline struct pbe *pack_orig_addresses(unsigned long *buf, struct pbe *pb int snapshot_read_next(struct snapshot_handle *handle, size_t count) { - if (handle->page > nr_meta_pages + nr_copy_pages) + if (handle->cur > nr_meta_pages + nr_copy_pages) return 0; if (!buffer) { /* This makes the buffer be freed by swsusp_free() */ @@ -568,8 +568,8 @@ int snapshot_read_next(struct snapshot_handle *handle, size_t count) handle->buffer = buffer; handle->pbe = pagedir_nosave; } - if (handle->prev < handle->page) { - if (handle->page <= nr_meta_pages) { + if (handle->prev < handle->cur) { + if (handle->cur <= nr_meta_pages) { handle->pbe = pack_orig_addresses(buffer, handle->pbe); if (!handle->pbe) handle->pbe = pagedir_nosave; @@ -577,15 +577,15 @@ int snapshot_read_next(struct snapshot_handle *handle, size_t count) handle->buffer = (void *)handle->pbe->address; handle->pbe = handle->pbe->next; } - handle->prev = handle->page; + handle->prev = handle->cur; } - handle->buf_offset = handle->page_offset; - if (handle->page_offset + count >= PAGE_SIZE) { - count = PAGE_SIZE - handle->page_offset; - handle->page_offset = 0; - handle->page++; + handle->buf_offset = handle->cur_offset; + if (handle->cur_offset + count >= PAGE_SIZE) { + count = PAGE_SIZE - handle->cur_offset; + handle->cur_offset = 0; + handle->cur++; } else { - handle->page_offset += count; + handle->cur_offset += count; } handle->offset += count; return count; @@ -820,7 +820,7 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count) { int error = 0; - if (handle->prev && handle->page > nr_meta_pages + nr_copy_pages) + if (handle->prev && handle->cur > nr_meta_pages + nr_copy_pages) return 0; if (!buffer) { /* This makes the buffer be freed by swsusp_free() */ @@ -831,7 +831,7 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count) if (!handle->offset) handle->buffer = buffer; handle->sync_read = 1; - if (handle->prev < handle->page) { + if (handle->prev < handle->cur) { if (!handle->prev) { error = load_header(handle, (struct swsusp_info *)buffer); @@ -854,15 +854,15 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count) handle->buffer = get_buffer(handle); handle->sync_read = 0; } - handle->prev = handle->page; + handle->prev = handle->cur; } - handle->buf_offset = handle->page_offset; - if (handle->page_offset + count >= PAGE_SIZE) { - count = PAGE_SIZE - handle->page_offset; - handle->page_offset = 0; - handle->page++; + handle->buf_offset = handle->cur_offset; + if (handle->cur_offset + count >= PAGE_SIZE) { + count = PAGE_SIZE - handle->cur_offset; + handle->cur_offset = 0; + handle->cur++; } else { - handle->page_offset += count; + handle->cur_offset += count; } handle->offset += count; return count; @@ -871,5 +871,5 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count) int snapshot_image_loaded(struct snapshot_handle *handle) { return !(!handle->pbe || handle->pbe->next || !nr_copy_pages || - handle->page <= nr_meta_pages + nr_copy_pages); + handle->cur <= nr_meta_pages + nr_copy_pages); } |