From 98441973105b80e133fcaa47ebf17be1e024ea30 Mon Sep 17 00:00:00 2001 From: Sarah Sharp Date: Thu, 14 May 2009 11:44:18 -0700 Subject: USB: xhci: Remove packed attribute from structures. The packed attribute allows gcc to muck with the alignment of data structures, which may lead to byte-wise writes that break atomicity of writes. Packed should only be used when the compile may add undesired padding to the structure. Each element of the structure will be aligned by C based on its size and the size of the elements around it. E.g. a u64 would be aligned on an 8 byte boundary, the next u32 would be aligned on a four byte boundary, etc. Since most of the xHCI structures contain only u32 bit values, removing the packed attribute for them should be harmless. (A future patch will change some of the twin 32-bit address fields to one 64-bit field, but all those places have an even number of 32-bit fields before them, so the alignment should be correct.) Add BUILD_BUG_ON statements to check that the compiler doesn't add padding to the data structures that have a hardware-defined layout. While we're modifying the registers, change the name of intr_reg to xhci_intr_reg to avoid global conflicts. Signed-off-by: Sarah Sharp Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/xhci-hcd.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'drivers/usb/host/xhci-hcd.c') diff --git a/drivers/usb/host/xhci-hcd.c b/drivers/usb/host/xhci-hcd.c index c6b921994b2..59ee61d2a19 100644 --- a/drivers/usb/host/xhci-hcd.c +++ b/drivers/usb/host/xhci-hcd.c @@ -1243,6 +1243,25 @@ static int __init xhci_hcd_init(void) return retval; } #endif + /* + * Check the compiler generated sizes of structures that must be laid + * out in specific ways for hardware access. + */ + BUILD_BUG_ON(sizeof(struct xhci_doorbell_array) != 256*32/8); + BUILD_BUG_ON(sizeof(struct xhci_slot_ctx) != 8*32/8); + BUILD_BUG_ON(sizeof(struct xhci_ep_ctx) != 8*32/8); + /* xhci_device_control has eight fields, and also + * embeds one xhci_slot_ctx and 31 xhci_ep_ctx + */ + BUILD_BUG_ON(sizeof(struct xhci_device_control) != (8+8+8*31)*32/8); + BUILD_BUG_ON(sizeof(struct xhci_stream_ctx) != 4*32/8); + BUILD_BUG_ON(sizeof(union xhci_trb) != 4*32/8); + BUILD_BUG_ON(sizeof(struct xhci_erst_entry) != 4*32/8); + BUILD_BUG_ON(sizeof(struct xhci_cap_regs) != 7*32/8); + BUILD_BUG_ON(sizeof(struct xhci_intr_reg) != 8*32/8); + /* xhci_run_regs has eight fields and embeds 128 xhci_intr_regs */ + BUILD_BUG_ON(sizeof(struct xhci_run_regs) != (8+8*128)*32/8); + BUILD_BUG_ON(sizeof(struct xhci_doorbell_array) != 256*32/8); return 0; } module_init(xhci_hcd_init); -- cgit v1.2.3