| Message ID | 20171127154955.22214-4-niklas.cassel@axis.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Mon, Nov 27, 2017 at 04:49:55PM +0100, Niklas Cassel wrote: > find_first_zero_bit()'s parameter 'size' is defined in bits, > not in bytes. > > Calling find_first_zero_bit() with the wrong size unit > will lead to insidious bugs. > > Fix this by calling find_first_zero_bit() with size BITS_PER_LONG, > rather than sizeof(). > > Also add proper error handling for find_first_zero_bit(), since this > was missing. "Fix this by calling find_first_zero_bit() with size BITS_PER_LONG, rather than sizeof() and add missing find_first_zero_bit() return handling" > Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions") > Signed-off-by: Niklas Cassel <niklas.cassel@axis.com> > --- > drivers/pci/endpoint/pci-ep-cfs.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c > index e1f5adc9e113..0a22a7976580 100644 > --- a/drivers/pci/endpoint/pci-ep-cfs.c > +++ b/drivers/pci/endpoint/pci-ep-cfs.c > @@ -109,7 +109,12 @@ static int pci_epc_epf_link(struct config_item *epc_item, > return ret; > > func_no = find_first_zero_bit(&epc_group->function_num_map, > - sizeof(epc_group->function_num_map)); > + BITS_PER_LONG); > + if (func_no >= BITS_PER_LONG) { > + ret = -EINVAL; > + dev_err(&epc->dev, "failed to link endpoint function device\n"); I would not log the error for the time being or make it more explicit: dev_error(&epc->dev, "unsupported number of functions, failed to link endpoint function device\n"); Side note: we _do_ know the max number of functions the epc supports (epc->max_functions) when this code is called so we do know the bitmap size - we can rework this code path based on that (@kishon, thoughts ?). Other than that: Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > + goto err_func_no; > + } > set_bit(func_no, &epc_group->function_num_map); > epf->func_no = func_no; > > @@ -121,6 +126,7 @@ static int pci_epc_epf_link(struct config_item *epc_item, > > err_epf_bind: > clear_bit(func_no, &epc_group->function_num_map); > +err_func_no: > pci_epc_remove_epf(epc, epf); > > return ret; > -- > 2.14.2 >
From: Niklas Cassel > Sent: 27 November 2017 15:50 > find_first_zero_bit()'s parameter 'size' is defined in bits, > not in bytes. > > Calling find_first_zero_bit() with the wrong size unit > will lead to insidious bugs. > > Fix this by calling find_first_zero_bit() with size > BITS_PER_LONG, rather than sizeof(). > > Also add proper error handling for find_first_zero_bit(), > since this was missing. > > Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions") > Signed-off-by: Niklas Cassel <niklas.cassel@axis.com> > --- > drivers/pci/endpoint/pci-ep-cfs.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c > index e1f5adc9e113..0a22a7976580 100644 > --- a/drivers/pci/endpoint/pci-ep-cfs.c > +++ b/drivers/pci/endpoint/pci-ep-cfs.c > @@ -109,7 +109,12 @@ static int pci_epc_epf_link(struct config_item *epc_item, > return ret; > > func_no = find_first_zero_bit(&epc_group->function_num_map, > - sizeof(epc_group->function_num_map)); > + BITS_PER_LONG); Surely this should be either 8 * sizeof() or you should use ffz() that takes a numeric argument rather than the function designed for arbitrary size bitmaps. David
On Tue, Nov 28, 2017 at 09:53:12AM +0000, David Laight wrote: > From: Niklas Cassel > > Sent: 27 November 2017 15:50 > > find_first_zero_bit()'s parameter 'size' is defined in bits, > > not in bytes. > > > > Calling find_first_zero_bit() with the wrong size unit > > will lead to insidious bugs. > > > > Fix this by calling find_first_zero_bit() with size > > BITS_PER_LONG, rather than sizeof(). > > > > Also add proper error handling for find_first_zero_bit(), > > since this was missing. > > > > Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions") > > Signed-off-by: Niklas Cassel <niklas.cassel@axis.com> > > --- > > drivers/pci/endpoint/pci-ep-cfs.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c > > index e1f5adc9e113..0a22a7976580 100644 > > --- a/drivers/pci/endpoint/pci-ep-cfs.c > > +++ b/drivers/pci/endpoint/pci-ep-cfs.c > > @@ -109,7 +109,12 @@ static int pci_epc_epf_link(struct config_item *epc_item, > > return ret; > > > > func_no = find_first_zero_bit(&epc_group->function_num_map, > > - sizeof(epc_group->function_num_map)); > > + BITS_PER_LONG); > > Surely this should be either 8 * sizeof() or you should use ffz() > that takes a numeric argument rather than the function designed > for arbitrary size bitmaps. Do you see a problem with this code ? It can be made a bitmap by allocating it using epc->max_functions as bitmap number of bits and that can be made on top of the code above that would go in as a fix unless you strongly object to it, as Joe mentioned both ffz+| and find_first_zero_bit()+set_bit() are ok with me as long as we choose one and fix the issue. Thanks, Lorenzo
diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c index e1f5adc9e113..0a22a7976580 100644 --- a/drivers/pci/endpoint/pci-ep-cfs.c +++ b/drivers/pci/endpoint/pci-ep-cfs.c @@ -109,7 +109,12 @@ static int pci_epc_epf_link(struct config_item *epc_item, return ret; func_no = find_first_zero_bit(&epc_group->function_num_map, - sizeof(epc_group->function_num_map)); + BITS_PER_LONG); + if (func_no >= BITS_PER_LONG) { + ret = -EINVAL; + dev_err(&epc->dev, "failed to link endpoint function device\n"); + goto err_func_no; + } set_bit(func_no, &epc_group->function_num_map); epf->func_no = func_no; @@ -121,6 +126,7 @@ static int pci_epc_epf_link(struct config_item *epc_item, err_epf_bind: clear_bit(func_no, &epc_group->function_num_map); +err_func_no: pci_epc_remove_epf(epc, epf); return ret;
find_first_zero_bit()'s parameter 'size' is defined in bits, not in bytes. Calling find_first_zero_bit() with the wrong size unit will lead to insidious bugs. Fix this by calling find_first_zero_bit() with size BITS_PER_LONG, rather than sizeof(). Also add proper error handling for find_first_zero_bit(), since this was missing. Fixes: d74679911610 ("PCI: endpoint: Introduce configfs entry for configuring EP functions") Signed-off-by: Niklas Cassel <niklas.cassel@axis.com> --- drivers/pci/endpoint/pci-ep-cfs.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)