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Violators will be prosecuted for from ; Wed, 22 Feb 2017 16:01:27 -0000 From: Halil Pasic Date: Wed, 22 Feb 2017 17:01:16 +0100 In-Reply-To: <20170222160119.52771-1-pasic@linux.vnet.ibm.com> References: <20170222160119.52771-1-pasic@linux.vnet.ibm.com> Message-Id: <20170222160119.52771-3-pasic@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH v2 2/5] migration/vmstate: split up vmstate_base_addr List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, "Dr. David Alan Gilbert" Cc: Juan Quintela , Amit Shah , Halil Pasic Currently vmstate_base_addr does several things: it pinpoints the field within the struct, possibly allocates memory and possibly does the first pointer dereference. Obviously allocation is needed only for load. Let us split up the functionality in vmstate_base_addr and move the address manipulations (that is everything but the allocation logic) to load and save so it becomes more obvious what is actually going on. Like this all the address calculations (and the handling of the flags controlling these) is in one place and the sequence is more obvious. The newly introduced function vmstate_handle_alloc also fixes the allocation for the unused VMS_VBUFFER|VMS_MULTIPLY|VMS_ALLOC scenario and is substantially simpler than the original vmstate_base_addr. In load and save some asserts are added so it's easier to debug situations where we would end up with a null pointer dereference. Signed-off-by: Halil Pasic Reviewed-by: Dr. David Alan Gilbert --- migration/vmstate.c | 39 +++++++++++++++++---------------------- 1 file changed, 17 insertions(+), 22 deletions(-) diff --git a/migration/vmstate.c b/migration/vmstate.c index 36efa80..836a7a4 100644 --- a/migration/vmstate.c +++ b/migration/vmstate.c @@ -52,29 +52,15 @@ static int vmstate_size(void *opaque, VMStateField *field) return size; } -static void *vmstate_base_addr(void *opaque, VMStateField *field, bool alloc) +static void vmstate_handle_alloc(void *ptr, VMStateField *field, void *opaque) { - void *base_addr = opaque + field->offset; - - if (field->flags & VMS_POINTER) { - if (alloc && (field->flags & VMS_ALLOC)) { - gsize size = 0; - if (field->flags & VMS_VBUFFER) { - size = vmstate_size(opaque, field); - } else { - int n_elems = vmstate_n_elems(opaque, field); - if (n_elems) { - size = n_elems * field->size; - } - } - if (size) { - *(void **)base_addr = g_malloc(size); - } + if (field->flags & VMS_POINTER && field->flags & VMS_ALLOC) { + gsize size = vmstate_size(opaque, field); + size *= vmstate_n_elems(opaque, field); + if (size) { + *(void **)ptr = g_malloc(size); } - base_addr = *(void **)base_addr; } - - return base_addr; } int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd, @@ -116,10 +102,15 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd, field->field_exists(opaque, version_id)) || (!field->field_exists && field->version_id <= version_id)) { - void *first_elem = vmstate_base_addr(opaque, field, true); + void *first_elem = opaque + field->offset; int i, n_elems = vmstate_n_elems(opaque, field); int size = vmstate_size(opaque, field); + vmstate_handle_alloc(first_elem, field, opaque); + if (field->flags & VMS_POINTER) { + first_elem = *(void **)first_elem; + assert(first_elem || !n_elems); + } for (i = 0; i < n_elems; i++) { void *curr_elem = first_elem + size * i; @@ -321,13 +312,17 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd, while (field->name) { if (!field->field_exists || field->field_exists(opaque, vmsd->version_id)) { - void *first_elem = vmstate_base_addr(opaque, field, false); + void *first_elem = opaque + field->offset; int i, n_elems = vmstate_n_elems(opaque, field); int size = vmstate_size(opaque, field); int64_t old_offset, written_bytes; QJSON *vmdesc_loop = vmdesc; trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems); + if (field->flags & VMS_POINTER) { + first_elem = *(void **)first_elem; + assert(first_elem || !n_elems); + } for (i = 0; i < n_elems; i++) { void *curr_elem = first_elem + size * i; -- 2.8.4