Re: [PATCH] Fix display of Maximum Memory
On 1/14/20 11:41 PM, Christophe Leroy wrote: > > > Le 14/01/2020 à 22:07, Michael Bringmann a écrit : >> Correct overflow problem in calculation+display of Maximum Memory >> value to syscfg where 32bits is insufficient. >> >> Signed-off-by: Michael Bringmann >> --- >> arch/powerpc/platforms/pseries/lparcfg.c | 8 >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/arch/powerpc/platforms/pseries/lparcfg.c >> b/arch/powerpc/platforms/pseries/lparcfg.c >> index 4ee2594..183aeb7 100644 >> --- a/arch/powerpc/platforms/pseries/lparcfg.c >> +++ b/arch/powerpc/platforms/pseries/lparcfg.c >> @@ -435,12 +435,12 @@ static void parse_em_data(struct seq_file *m) >> >> static void maxmem_data(struct seq_file *m) >> { >> - unsigned long maxmem = 0; >> + unsigned long long maxmem = 0; > > What about using u64 instead, for readability ? Okay. > >> >> - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size; >> - maxmem += hugetlb_total_pages() * PAGE_SIZE; >> + maxmem += (unsigned long long)drmem_info->n_lmbs * (unsigned long >> long)drmem_info->lmb_size; > > This line is likely too long. You only need to cast one of the two operants > to force a 64 bits multiply. And using u64 would shorten the line. > > Can both multiplications overflow ? Yes. > > Christophe > >> + maxmem += (unsigned long long)hugetlb_total_pages() * (unsigned long >> long)PAGE_SIZE; >> >> - seq_printf(m, "MaxMem=%ld\n", maxmem); >> + seq_printf(m, "MaxMem=%llu\n", maxmem); >> } >> >> static int pseries_lparcfg_data(struct seq_file *m, void *v) >> > Thanks. -- Michael W. Bringmann Linux Technology Center IBM Corporation Tie-Line 363-5196 External: (512) 286-5196 Cell: (512) 466-0650 m...@linux.ibm.com
Re: [PATCH] Fix display of Maximum Memory
Le 14/01/2020 à 22:07, Michael Bringmann a écrit : Correct overflow problem in calculation+display of Maximum Memory value to syscfg where 32bits is insufficient. Signed-off-by: Michael Bringmann --- arch/powerpc/platforms/pseries/lparcfg.c | 8 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c index 4ee2594..183aeb7 100644 --- a/arch/powerpc/platforms/pseries/lparcfg.c +++ b/arch/powerpc/platforms/pseries/lparcfg.c @@ -435,12 +435,12 @@ static void parse_em_data(struct seq_file *m) static void maxmem_data(struct seq_file *m) { - unsigned long maxmem = 0; + unsigned long long maxmem = 0; What about using u64 instead, for readability ? - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size; - maxmem += hugetlb_total_pages() * PAGE_SIZE; + maxmem += (unsigned long long)drmem_info->n_lmbs * (unsigned long long)drmem_info->lmb_size; This line is likely too long. You only need to cast one of the two operants to force a 64 bits multiply. And using u64 would shorten the line. Can both multiplications overflow ? Christophe + maxmem += (unsigned long long)hugetlb_total_pages() * (unsigned long long)PAGE_SIZE; - seq_printf(m, "MaxMem=%ld\n", maxmem); + seq_printf(m, "MaxMem=%llu\n", maxmem); } static int pseries_lparcfg_data(struct seq_file *m, void *v)
[PATCH] Fix display of Maximum Memory
Correct overflow problem in calculation+display of Maximum Memory value to syscfg where 32bits is insufficient. Signed-off-by: Michael Bringmann --- arch/powerpc/platforms/pseries/lparcfg.c | 8 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c index 4ee2594..183aeb7 100644 --- a/arch/powerpc/platforms/pseries/lparcfg.c +++ b/arch/powerpc/platforms/pseries/lparcfg.c @@ -435,12 +435,12 @@ static void parse_em_data(struct seq_file *m) static void maxmem_data(struct seq_file *m) { - unsigned long maxmem = 0; + unsigned long long maxmem = 0; - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size; - maxmem += hugetlb_total_pages() * PAGE_SIZE; + maxmem += (unsigned long long)drmem_info->n_lmbs * (unsigned long long)drmem_info->lmb_size; + maxmem += (unsigned long long)hugetlb_total_pages() * (unsigned long long)PAGE_SIZE; - seq_printf(m, "MaxMem=%ld\n", maxmem); + seq_printf(m, "MaxMem=%llu\n", maxmem); } static int pseries_lparcfg_data(struct seq_file *m, void *v) -- 1.8.3.1