Messages in this thread | | | Date | Wed, 13 Jul 2022 20:28:24 +0200 | From | Greg KH <> | Subject | Re: [PATCH v2 1/1] misc: hpilo: switch .{read,write} ops to .{read,write}_iter |
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On Thu, Jul 14, 2022 at 01:54:52AM +0800, matt.hsiao@hpe.com wrote: > From: Matt Hsiao <matt.hsiao@hpe.com> > > Commit 4d03e3cc59828c82ee89 ("fs: don't allow kernel reads and writes > without iter ops") requested exclusive .{read,write}_iter ops for > kernel_{read,write}. To support dependent drivers to access hpilo by > kernel_{read,write}, switch .{read,write} ops to their iter variants. > > Signed-off-by: Matt Hsiao <matt.hsiao@hpe.com>
So this fixes a bug? What commit does this fix?
Should it go to stable branches? If so, which ones?
But my main question is I have no idea what the changelog means here. What is a "dependent driver"? What does "exclusive" mean here? What is a iter variant?
> --- > drivers/misc/hpilo.c | 31 ++++++++++++++++++------------- > 1 file changed, 18 insertions(+), 13 deletions(-) > > diff --git a/drivers/misc/hpilo.c b/drivers/misc/hpilo.c > index 8d00df9243c4..5d431a56b7eb 100644 > --- a/drivers/misc/hpilo.c > +++ b/drivers/misc/hpilo.c > @@ -23,6 +23,7 @@ > #include <linux/wait.h> > #include <linux/poll.h> > #include <linux/slab.h> > +#include <linux/uio.h> > #include "hpilo.h" > > static struct class *ilo_class; > @@ -435,14 +436,14 @@ static void ilo_set_reset(struct ilo_hwinfo *hw) > } > } > > -static ssize_t ilo_read(struct file *fp, char __user *buf, > - size_t len, loff_t *off) > +static ssize_t ilo_read_iter(struct kiocb *iocb, struct iov_iter *to) > { > - int err, found, cnt, pkt_id, pkt_len; > - struct ccb_data *data = fp->private_data; > + int err = 0, found, cnt, pkt_id, pkt_len; > + struct ccb_data *data = iocb->ki_filp->private_data; > struct ccb *driver_ccb = &data->driver_ccb; > struct ilo_hwinfo *hw = data->ilo_hw; > void *pkt; > + size_t len = iov_iter_count(to), copied; > > if (is_channel_reset(driver_ccb)) { > /* > @@ -477,7 +478,9 @@ static ssize_t ilo_read(struct file *fp, char __user *buf, > if (pkt_len < len) > len = pkt_len; > > - err = copy_to_user(buf, pkt, len); > + copied = copy_to_iter(pkt, len, to); > + if (unlikely(copied != len))
Why unlikely? If you can prove it is needed in benchmarks, great, otherwise never add likely/unlikely as they are almost always wrong and the compiler and cpu can do it better.
> + err = -EFAULT; > > /* return the received packet to the queue */ > ilo_pkt_enqueue(hw, driver_ccb, RECVQ, pkt_id, desc_mem_sz(1)); > @@ -485,14 +488,14 @@ static ssize_t ilo_read(struct file *fp, char __user *buf, > return err ? -EFAULT : len; > } > > -static ssize_t ilo_write(struct file *fp, const char __user *buf, > - size_t len, loff_t *off) > +static ssize_t ilo_write_iter(struct kiocb *iocb, struct iov_iter *from) > { > - int err, pkt_id, pkt_len; > - struct ccb_data *data = fp->private_data; > + int err = 0, pkt_id, pkt_len; > + struct ccb_data *data = iocb->ki_filp->private_data; > struct ccb *driver_ccb = &data->driver_ccb; > struct ilo_hwinfo *hw = data->ilo_hw; > void *pkt; > + size_t len = iov_iter_count(from), copied; > > if (is_channel_reset(driver_ccb)) > return -ENODEV; > @@ -506,9 +509,11 @@ static ssize_t ilo_write(struct file *fp, const char __user *buf, > len = pkt_len; > > /* on failure, set the len to 0 to return empty packet to the device */ > - err = copy_from_user(pkt, buf, len); > - if (err) > + copied = copy_from_iter(pkt, len, from); > + if (unlikely(copied != len)) {
Same here.
thanks,
greg k-h
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