Hi Florian, thanks for your review! On mer., janv. 27 2016, Florian Fainelli <f.faine...@gmail.com> wrote:
> On 12/01/16 11:10, Gregory CLEMENT wrote: >> This basic implementation allows to share code between driver using >> hardware buffer management. As the code is hardware agnostic, there is >> few helpers, most of the optimization brought by the an HW BM has to be >> done at driver level. >> >> Signed-off-by: Gregory CLEMENT <gregory.clem...@free-electrons.com> >> --- >> include/net/hwbm.h | 19 +++++++++++++ >> net/core/Makefile | 2 +- >> net/core/hwbm.c | 78 >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 98 insertions(+), 1 deletion(-) >> create mode 100644 include/net/hwbm.h >> create mode 100644 net/core/hwbm.c >> >> diff --git a/include/net/hwbm.h b/include/net/hwbm.h >> new file mode 100644 >> index 000000000000..898ccd2fb58d >> --- /dev/null >> +++ b/include/net/hwbm.h >> @@ -0,0 +1,19 @@ >> +#ifndef _HWBM_H >> +#define _HWBM_H >> + >> +struct hwbm_pool { >> + /* Size of the buffers managed */ >> + int size; >> + /* Number of buffers currently used by this pool */ >> + int buf_num; >> + /* constructor called during alocation */ >> + int (*construct)(struct hwbm_pool *bm_pool, void *buf); > > Having the buffer size might be handy too. > >> + /* private data */ >> + void *priv; >> +}; >> + >> +void hwbm_buf_free(struct hwbm_pool *bm_pool, void *buf); >> +int hwbm_pool_refill(struct hwbm_pool *bm_pool); >> +int hwbm_pool_add(struct hwbm_pool *bm_pool, int buf_num); >> + >> +#endif /* _HWBM_H */ >> diff --git a/net/core/Makefile b/net/core/Makefile >> index 0b835de04de3..df81bf11f072 100644 >> --- a/net/core/Makefile >> +++ b/net/core/Makefile >> @@ -9,7 +9,7 @@ obj-$(CONFIG_SYSCTL) += sysctl_net_core.o >> >> obj-y += dev.o ethtool.o dev_addr_lists.o dst.o >> netevent.o \ >> neighbour.o rtnetlink.o utils.o link_watch.o filter.o \ >> - sock_diag.o dev_ioctl.o tso.o sock_reuseport.o >> + sock_diag.o dev_ioctl.o tso.o sock_reuseport.o hwbm.o > > Not everybody will want this built in by default, we probably need a > hidden config symbol here. I copied what was done for TSO, but I agree to not build it by default. > >> >> obj-$(CONFIG_XFRM) += flow.o >> obj-y += net-sysfs.o >> diff --git a/net/core/hwbm.c b/net/core/hwbm.c >> new file mode 100644 >> index 000000000000..d5d40d63cb34 >> --- /dev/null >> +++ b/net/core/hwbm.c >> @@ -0,0 +1,78 @@ >> +/* Support for hardware buffer manager. >> + * >> + * Copyright (C) 2016 Marvell >> + * >> + * Gregory CLEMENT <gregory.clem...@free-electrons.com> >> + * >> + * This program is free software; you can redistribute it and/or modify >> + * it under the terms of the GNU General Public License as published by >> + * the Free Software Foundation; either version 2 of the License, or >> + * (at your option) any later version. >> + */ >> +#include <linux/kernel.h> >> +#include <linux/printk.h> >> +#include <linux/skbuff.h> >> +#include <net/hwbm.h> >> + >> +void hwbm_buf_free(struct hwbm_pool *bm_pool, void *buf) >> +{ >> + if (likely(bm_pool->size <= PAGE_SIZE)) >> + skb_free_frag(buf); >> + else >> + kfree(buf); >> +} >> +EXPORT_SYMBOL_GPL(hwbm_buf_free); >> + >> +/* Refill processing for HW buffer management */ >> +int hwbm_pool_refill(struct hwbm_pool *bm_pool) >> +{ >> + void *buf; >> + int frag_size = bm_pool->size; > > Reverse christmas tree declaration looks a bit nicer. First time I heard about it :) I though it was something related to the tree algorithms until I visualized it! My logical here was first uninitialized variable then the initialized ones. But I don't have a strong opinion about it so I can change it. > >> + >> + if (likely(frag_size <= PAGE_SIZE)) >> + buf = netdev_alloc_frag(frag_size); >> + else >> + buf = kmalloc(frag_size, GFP_ATOMIC); > > Maybe we should allow the caller to specify a gfp_t, just in case > GFP_ATOMIC is not good enough. Good idea. > >> + >> + if (!buf) >> + return -ENOMEM; >> + >> + if (bm_pool->construct) >> + if (bm_pool->construct(bm_pool, buf)) { >> + hwbm_buf_free(bm_pool, buf); >> + return -ENOMEM; >> + } >> + >> + return 0; >> +} >> +EXPORT_SYMBOL_GPL(hwbm_pool_refill); >> + >> +int hwbm_pool_add(struct hwbm_pool *bm_pool, int buf_num) > > unsigned int buf_num OK > >> +{ >> + int err, i; >> + >> + if (bm_pool->buf_num == bm_pool->size) { >> + pr_debug("pool already filled\n"); >> + return bm_pool->buf_num; >> + } >> + >> + if (buf_num + bm_pool->buf_num > bm_pool->size) { >> + pr_debug("cannot allocate %d buffers for pool\n", >> + buf_num); >> + return 0; >> + } > > buf_num is under caller control, and potentially hardware control > indirectly, what if I make this arbitrary big and wrap around? We could test if ((buf_num + bm_pool->buf_num)<bm_pool->buf_num. I failed to find a better way to detect a wrapping. > >> + >> + for (i = 0; i < buf_num; i++) { >> + err = hwbm_pool_refill(bm_pool); >> + if (err < 0) >> + break; >> + } > > If we fail refiling here, should not we propagate the error back to the > caller? We return the number of we actually managed to add. So, if it fails we return less buffer than expected, as for a read in userspace. Is it not a good indication of what happened? > >> + >> + /* Update BM driver with number of buffers added to pool */ >> + bm_pool->buf_num += i; >> + >> + pr_debug("hwpm pool: %d of %d buffers added\n", i, buf_num); > > No locking or atomic operations here? What if two CPUs call into this > function? Indeed it could be a problem, I will see how to handle this in the next version. Thanks again, Gregory > >> + >> + return i; >> +} >> +EXPORT_SYMBOL_GPL(hwbm_pool_add); >> > > > -- > Florian -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com